How is Hess's law applied in calculating enthalpy?
A. The first and last reactions in a path are added together.
B. Similar equations are substituted for unknown reactions.
OC. All the reactions in a path are added together.
D. The final equation in a path from reactants to products is used.
SUBMIT

The formula for ionic compound always indicate empirical formula. Empirical formula is the lowest number of the condition of the element present in a compound..

Empirical formula is formula represent the minimum condition of the reaction to happen between element. Empirical formula is commonly use to calculate the important value of a compound such as:

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Answer:

the reaction is synthesis When two or more simple compounds combine to form a more complicated one. This is also known as a direct combination reaction.

Explanation:

The limiting reactant if 4. 0 g of nh3 react with 8. 0 g of oxygen is Oxygen because  it produces only 0. 20 mol of NO. the option A is correct.

The reactant that is present in a chemical reaction at a lower concentration than the other reactant and determines the production of the product is known as the limiting reactant.

Ammonia dissociation's balanced equation is:

4NH₃ +5O₂⇒ 4NO +6H₂O

To react with 5 moles of oxygen, 4 moles of ammonia are needed.

The moles are listed as:

moles = mass/ mass molar

The available moles of ammonia in 4 gram is:

moles NH₃ = 4 /17 = 0.23 moles

moles oxygen = 8 / 16 = 0.25 moles

The moles of oxygen required for 0.23 moles of ammonia are:

5/4 x 0.23 = 0.28 moles

The amount of oxygen that is needed is 0.28 mol, yet there are only 0.25 mol of oxygen that are readily available. So, the limiting reagent is oxygen.

Therefore, choice A is right.

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True- Alchemists tried to turn metals into gold. True-If the medicines have been evaluated using unbiased tests.

True- A medieval pseudoscience that tried to find ways to change ordinary metals into gold.

Alchemy is a historical philosophical and proto scientific tradition that was practiced in China, India, the Muslim world, and Europe. It is an old branch of natural philosophy also.

In the early few centuries AD, a handful of pseudo epigraphical works produced in Greco-Roman Egypt are the first to mention alchemy in its Western form.

Which inference can be made from the fact that Fritz Haber received a Nobel Prize in 1918

The Haber-Bosch process was used to make explosives in World War I and The Haber-Bosch process was an important scientific development.

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The mass of an additional 0.5% sodium chloride is 2.93×10^23

As an electrolyte replenisher, sodium chloride is used to assist reduce heat cramps brought on by excessive sweating. This drug is also used to make a standard isotonic sodium chloride solution. The chemical formula for the ionic compound sodium chloride, often known as salt, is NaCl, which represents a 1:1 ratio of the ions sodium and chloride. 39.34 g Na and 60.66 g Cl have molar weights of 22.99 and 35.45 g/mol in 100 g of NaCl, respectively. To replace salt and water that have been lost from your body as a result of specific conditions, sodium chloride 23.4% injection is employed (eg, hyponatremia or low salt syndrome). Additionally, it is added to IV fluids that contain carbohydrates and total parenteral nutrition (TPN).

In vulnerable individuals, a high-NaCl diet can increase blood pressure and result in premature mortality. In hypertension, a high-NaCl diet can significantly increase mortality even while it does not further raise blood pressure, in part due to numerous tiny brain infarcts, according to recent research. Salt, commonly known as sodium chloride (NaCl), is a crucial substance that our body uses to transport and absorb nutrients. keep blood pressure steady. maintain the proper fluid equilibrium.

Molecular formula of NaCl is 58.5

58.5gof NaCl=6.023×10^23

28.5g of NaCl= 6.023×10^23÷58.5×28.5

= 2.93×10^23

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The internal structure and external features of organisms have evolved to enhance their survival in various ways.

Internal structure refers to the internal organs and systems of an organism, such as the circulatory, respiratory, and nervous systems. These systems work together to maintain the organism's homeostasis, or internal balance, which is necessary for survival.

For example, the circulatory system transports oxygen and nutrients to cells, while the respiratory system removes carbon dioxide and other waste products.

External features, such as body shape, coloration, and behavior, also play a role in an organism's survival. For example, camouflage can help an organism avoid predators, while bright colors can signal to potential mates. The shape of an organism can also be important for survival.

Overall, they work together to enhance the organism's chances of survival by allowing it to find food, avoid predators, and reproduce successfully.

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75% of the surface of the world is covered by water, yet only a small portion of that water, 97% of it being in the oceans, is suitable for use by people, animals, or plants since it is too salty.

Freshwater is defined as water with less than 1,000 milligrams of dissolved particles per liter, most frequently salt. Earth's surface water bodies are often seen as renewable resources because they are a part of the water cycle, despite the fact that they rely heavily on other water cycle components.

Freshwater is defined as water with less than 1,000 milligrams of dissolved particles per liter, most frequently salt. Earth's surface water bodies are involved in the water cycle.

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the oxidation number of the following is a. PO43-: Phosphorus: +5, Oxygen: -2, b. PO33-: Phosphorus: +3, Oxygen: -2, c. HPO42-: Hydrogen: +1, Phosphorus: +5, Oxygen: -2, d. P3O103-: Phosphorus: +5, Oxygen: -2, e. IO3-: Iodine: +5, Oxygen: -2, f. IO2-: Iodine: +4, Oxygen: -2.

g. IO-: Iodine: +1,h. NH4+: Nitrogen: +3, Hydrogen: +1, i. NO2+: Nitrogen: +4, Oxygen: -2, j. NO2-: Nitrogen: +3, Oxygen: -2, k. NO-: Nitrogen: +2, Oxygen: -2, l. NO3+: Nitrogen: +5, Oxygen: -2, m. N2O22-: Nitrogen: +5, Oxygen: -2, n. TeO42-: Tellurium: +6, Oxygen: -2, o. SiO22-: Silicon: +4, Oxygen: -2. The oxidation number (also called oxidation state) of an atom in a chemical compound is a number that represents the degree of oxidation (loss of electrons) of that atom. The oxidation number is assigned based on a set of rules, such as: The oxidation number of an atom in its elemental form is always 0. In a compound, the sum of the oxidation numbers of all atoms must be equal to the charge of the compound (if it is an ion) or 0 (if it is a neutral compound).

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It is possible to work on composition stoichiometry in your head because the reaction equations in composition stoichiometry are still simple.

A chemical reaction is a process in which one or more substances are converted into one or different substances and produce new products. The characteristics of a chemical reaction are a change in color or smell, gas or precipitate is formed, and there is a change in energy.

Stoichiometry is the science that studies the quantity of a substance in a chemical reaction. These substances include mass, number of moles, volume, and number of particles. In compositional stoichiometry you will understand the quantitative relationship between the masses or the amount of substance between elements in a compound. Like the amount of Nitrogen and Hydrogen substances that combine to form complex ammonia (NH3). So it allows you to calculate it in your brain because the reaction equation is still simple.

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Answer:

It describes the number of atoms in 1 mole of an element.

Explanation:

Avogadro's number is simply a definition of a very large number.  It is called a mole.   It has no physical units.  It simply means 6.02x10^23 of something.  Anything.  Atoms, molecules, paper clips, dollars, school buses, people waiting in line for a concert, etc.  Anything.  Similar words include billion, trillion, quintillion, picometer (look it up) and similar shorthand for very large numbers.  "Santa received 1.8 moles of letters this past year" is an easier way of saying that he received 1,080,000,000,000,000,000,000,000  (or 1.08x10^24) letters.   Publishers didn't like the idea that science books may be cluttered with such nonsense.  And scientists have more fun things to do than wrtite out such long numbers [correctly], so the mole was invented.  It's relationship to the Periodic Table and concept of molar mass is it's true value, but that isn't aksed in this question.

A chemical that releases hydrogen ions into water when coupled with certain metals to form salts.

A substance that, when combined with specific metals, creates salts by releasing hydrogen ions into water. Acids taste sour and cause some colours to turn red. Gastric acid is one of the body's natural acids, and it can support organ function. A substance is considered an acid if it tastes sour in aqueous solution, turns blue litmus paper red, reacts with some metals to release hydrogen, reacts with bases to produce salts, and fosters chemical reactions (acid catalysis).

A chemical that tastes sour and when added to water, produces hydrogen ions is referred to as an acid in science. Acids with a pH lower than 7 will cause litmus to turn red. Any material that when combined with hydrogen ions becomes an acid

weak acid:

HA ↔ H+  + A-

∴ Ka = 5 E-5 M = [H+][A-]/[HA]

∴ [HA] = 0.10 M - [A-]

∴ [H+] = [A-]

⇒ Ka = [H+]²/(0.10 - [H+])

substitute the values in the above equation we get

⇒ [H+]² + 5 E-5[H+] - 5 E-6 = 0

simplifying the above equation, we get

⇒ [H+] = 2.211 E-3 M

⇒ pH = - Log [H+]

⇒ pH = 2.6553

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Answer: Galena

Explanation:

(A). Galena

An unidentified mineral that is softer than calcite, exhibits a metallic luster and cubic cleavage. This mineral most likely is galena.

Talc, Gypsum, Calcite, Fluorite, Apatite, Feldspar, Quartz, Topaz, Corundum, and Diamond are just a few examples. - The "Mohs Scale of Mineral Hardness" lists common minerals in order of relative hardness, with talc being the softest and diamond being the hardest mineral. This scale should be familiar to rock hounds and earth science students alike.

When newly broken, galena is a metallic lead grey with a brilliant metallic shine; as it ages, it turns dark grey or black. It is incredibly hefty and fragile (about 7.6 times as heavy as water). Galena often crystallizes in cubic crystals and cleaves into flawless cubic pieces.

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A substance with a pH of 11 is 10 times more alkaline than a substance with a pH of 1.

The pH is a data that is used as a reference to classify chemical substances according to their alkalinity or acidity. The pH is measured on a scale from 0 to 14 that is divided as follows:

According to the above, it can be inferred that the substance that has a pH of 11 is not more acidic but alkaline. On the other hand, the substance with a pH of 1 is more acidic.

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Hydrogen

Magnesium

Iron

Helium

Sulfur

Copper

Aluminum

Argon

Xenon

etc.

Answer:

C

Explanation:

Don't think too much. Go with short to the point way... Melting point is always go with lowest point 80.2 degree C

The limiting reactant in this reaction is the baking soda (sodium bicarbonate).

A limiting reactant is a reactant in a chemical reaction that is completely consumed before the other reactants. It limits the amount of product that can be formed; the amount of product created is directly proportional to the amount of the limiting reactant present. The term is also known as the limiting reagent. This concept is used in stoichiometry, which is the calculation of the amount of product that can be formed from a given amount of reactants.

This is because it takes more moles of baking soda (NaHCO3) than vinegar (CH3COOH) to cause the reaction to occur. Since there are only 2.5g of baking soda present, it will be used up first and the reaction will stop once all the baking soda has been used.

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Three isotopes of carbon are found in nature: carbon 13, that has 7 neutrons, carbon 14, that has 8 neutrons, and carbon 12, that has 6 particles (plus 6 protons = 12).

A naturally occurring stable isotope that carbon with such a nucleus made up of six protons & seven neutrons is called carbon-13 (13C).

The amount of protons in an element's nucleus determines how it will react chemically.However, the amount or neutrons in the nucleus of different atoms in the same element might vary.

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A. Multiply - When converting from moles to particles or moles to grams, you must multiply.

Moles are small mammals that are found in many parts of the world. They are burrowing animals that live in underground tunnels and feed on insects, worms, and other small animals. Moles have small eyes and ears, and their fur is usually black or brown. They have large front feet with long claws that help them dig their tunnels. Moles are solitary animals and are active mainly at night. They are important to the environment because they aerate the soil and help control insect populations.

This is because moles are a unit of measurement that represent the number of particles or grams in a given substance. To convert from moles to particles or moles to grams, you must multiply the number of moles by the number of particles or grams in one mole of the substance.

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Surface mucous cells (foveolar cells), parietal cells, chief cells are the three main types of cells located in stomach.

The stomach lining is covered by these cells' thick mucus, which shields it from the digestive juices. The stomach lining is always protected because the surface mucous cells continuously regenerate.

The gastric pits, which are primarily found in the fundus, the upper region of the stomach, contain parietal cells. They release hydrochloric acid, which aids in the digestion of meals.

The fungus, where the gastric glands are located, contains chief cells. They release digestive enzymes that aid in food digestion. Pepsinogen is secreted by the main cells. In the presence of hydrochloric acid, it turns into pepsin. Pepsin aids in the breakdown of proteins into little molecules called polypeptides.

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The approximate bonding order of At and O can be predicted using the Lewis structure of Ato3

Lewis structure, also known as electron-dot framework, is a physical formula in which dots serve as placeholders for electrons; two dots across two atoms signify a covalent link. Gilbert Newton Lewis, the man behind its 1916 introduction, gave it its name.

The Lewis structure of water, or H2O, is shown here as an example. The atom's core electrons are represented by each symbol, along with the nucleus. A hydrogen atom's nucleus is represented by each "H" in this diagram, and an oxygen atom's nucleus and two core electrons are represented by each "O". The valence electrons in the dots are not in bonds.

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There would be 1.67 grams of water are produced if we react 3 moles of hydrogen with 3 moles of oxygen.

First we write the balanced reaction

2H₂ (g) + O₂ (g) → 2H₂O (l)

From the reaction we know that 2 moles of H₂ and 1 mole of O₂  produce 2 moles of 2H₂O. the limiting reactant is hydrogen, so we can use unitary method to calculate the moles of water produced

Moles of water= 2/2 x moles hydrogen

Moles of water = 2/2 x 3 moles = 3 moles

then we can calculate the mass of water produced

Mass water = mass/ mass molar

Mass water = 3 moles / 18 g/mol

mass water = 1.67 gram

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Strong heating has no effect on this substance. Long-term storage at room temperature is possible, but it must be kept dry because it interacts fast with moisture and water in the air.

On a large scale, it can be produced via the reaction of silicon or silicon carbide with iodine when heated to roughly 200 °C. The interaction of silane with iodine vapor at temperatures between 130 and 150 °C is of more academic interest because a variety of compounds, including iodosilane SiH3I, diiodosilane SiH2I2, and triiodosilane SiHI3, are produced. The liquid forms of these compounds are colorless at normal temperatures. [3] Iodoform, a related carbon compound that is a yellow solid at ambient temperature, can be easily separated from the final one.

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The example of the intermolecular forces is the hydrogen bonding. The hydrogen bonding means the formation of the hydrogen bond.

The formation of the hydrogen bond is the hydrogen bonding. The hydrogen bonding is the intermolecular force due to the dipole - dipole interaction. It arises due the interaction between the hydrogen atom and the more electronegative atom bonded to it. The example of the hydrogen bonding is the water , that is H₂O. The hydrogen atom is bonded to the more electronegative atom that is oxygen.

The hydrogen bonding are of the two types :

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The number of ammonia molecules made when 6 grams of hydrogen gas reacts with excess nitrogen is 1.79 * 10^24. So the answer is (a) 24 x 10 ^ 23

The balanced equation for the reaction of hydrogen gas (H2) with nitrogen gas (N2) to form ammonia (NH3) is:

2H2 + N2 -> 2NH3

If the reaction uses 6 grams of hydrogen gas, we can use the molar mass of hydrogen (2.02 g/mol) to find the number of moles of hydrogen used in the reaction:

6 g / 2.02 g/mol = 2.97 mol

Since the equation states that 2 moles of hydrogen are needed to produce 2 moles of ammonia, then 2.97 moles of hydrogen will produce 2.97 moles of ammonia.

To find the number of ammonia molecules, we multiply the number of moles by Avogadro's number:

2.97 mol * 6.022 * 10^23 molecules/mol = 1.79 * 10^24

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Replication is the process in which n two identical copies of DNA molecules are produced which are exactly the same as the original

It is the most basic step occuring in living organisms.

The opening of the double helix and separation of the DNA strands, priming of the template strand, and construction of the new DNA segment are the three main phases in replication.

The DNA double helix's two strands uncoil at a specific spot known as the origin during separation. Then, a number of proteins and enzymes combine to prime the strands for duplication. Finally, the building of the new DNA strands is organized by a unique enzyme known as DNA polymerase.

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According to the activity series , the chemical equation which is correct or chemical reaction  which will most likely take place  is Li + ZnCO₃ as Li is more reactive than zinc and it will displace Zn from   ZnCO₃.

Chemical equation is a symbolic representation of a chemical reaction which is written in the form of symbols and chemical formulas.The reactants are present on the left hand side while the products are present on the right hand side.

A plus sign is present between reactants and products if they are more than one in any case and an arrow is present pointing towards the product side which indicates the direction of the reaction .There are coefficients present next to the chemical symbols and formulas .

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A concentration cell is a cell in which the two half cells have the same electrodes but have the different concentration. so the correct option is e) none of these.

The concentration cell is the electrolytic cell that is made up of the two half - cells that have the same electrodes but different in the concentration. A concentration cell is dilute the concentrated solution and the concentrate more dilute solution. This creates the voltage when the cell reaches an equilibrium state.

Thus ,  a concentration cell is in which there is the two half cells and having the same electrodes. The concentration is different.

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Answer:

Explanation:

vdW radius (nm) ionic radius of X- (nm)

Cl 0.175          0.181

Br 0.185          0.196

I 0.198          0.220

5) The theoretical yield of H₂O is 36.04g.

6) The theoretical volume of CO2 produced is 0.005 L.

7) The mass of water produced is 0.981g.

The theoretical yield of a reaction is the maximum amount of product that can be produced from a given amount of reactants, assuming that the reaction goes to completion. To calculate the theoretical yield, we need to know the balanced equation for the reaction and the amounts of reactants used.

5) Given and unknown:

The balanced equation for the reaction is 2 H2(g) + O2(g) → 2 H₂O(1)

The amount of H2 used is 6

The amount of O2 used is 30g

Steps:

1.    Determine the limiting reactant: The limiting reactant is the reactant that will be completely consumed before the other reactant is consumed. In this case, the limiting reactant is H2 because 6g of H2 will react completely with 6g of O2, while 30g of O2 will still have some remaining.

2.    Calculate the theoretical yield of the product: The theoretical yield of H2O can be calculated by using the stoichiometry of the reaction. The balanced equation tells us that 2 moles of H2 react with 1 mole of O2 to form 2 moles of H2O. We can use the molar mass of H2 and O2 to convert the given mass of each reactant to moles, and then use the balanced equation to determine the theoretical yield of H2O.

Solution:

·         Molar mass of H2 = 2.02 g/mol

·         Molar mass of O2 = 32 g/mol

·         6g of H2 is equal to 6/2.02 = 2.97 moles

·         30g of O2 is equal to 30/32 = 0.9375 moles

·         Since H2 is the limiting reactant, the reaction will consume 2.97 moles of H2.

·         Using the balanced equation, 2 moles of H2 will produce 2 moles of H2O

·         Therefore, the theoretical yield of H2O is 2 x 18.02 = 36.04 g

·         Therefore, the theoretical yield of H₂O is 36.04g.

6) Given and unknown:

The balanced equation for the reaction is 2 C2H6(g) + 7 O2(g) → 6 H2O(l) + 4 CO2(g)

The volume of C2H6 used is 0.42L

The volume of O2 used is 3.12L

The unknown is the theoretical volume of CO2 produced

Steps:

Convert the volumes of reactants to moles using the ideal gas laws PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant and T is the temperature.

Determine the limiting reactant: The limiting reactant is the reactant that will be completely consumed before the other reactant is consumed.

Use the balanced equation to calculate the number of moles of CO2 produced.

Convert the moles of CO2 to volume using the ideal gas laws PV = nRT

Solution:

Ideal gas constant R = 8.314 J/mol*K

Temperature T = 298 K

Pressure P = 1 atm

Molar mass of C2H6 = 30.07 g/mol

Molar mass of O2 = 32 g/mol

Molar mass of CO2 = 44 g/mol

0.42L of C2H6 is equal to 0.42 x (1 x 10^3) / (8.314 x 298) = 0.0058 mol

3.12L of O2 is equal to 3.12 x (1 x 10^3) / (8.314 x 298) = 0.0433 mol

From the balanced equation, we can see that for every 2 moles of C2H6, 4 moles of CO2 are produced.

Therefore, 0.0058 mol of C2H6 will produce 0.0058 x 2 = 0.0116 mol of CO2

Finally, 0.0116 mol of CO2 will produce 0.0116 x (44/1000) = 0.005L of CO2.

Therefore, the theoretical volume of CO2 produced is 0.005 L

7) Given and unknown:

The balanced equation for the reaction is 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H₂O(1)

The mass of NH3 used is 1.54g

The mass of O2 used is 1.25g

The unknown is the mass of water produced

Steps:

Determine the limiting reactant: The limiting reactant is the reactant that will be completely consumed before the other reactant is consumed.

Use the balanced equation to calculate the number of moles of water produced.

Calculate the mass of water produced by using the molar mass of water

Solution:

Molar mass of NH3 = 17 g/mol

Molar mass of O2 = 32 g/mol

Molar mass of H2O = 18 g/mol

1.54g of NH3 is equal to 1.54 / 17 = 0.0906 mol

1.25g of O2 is equal to 1.25 / 32 = 0.0391 mol

From the balanced equation, we can see that for every 4 moles of NH3, 6 moles of H2O are produced.

Therefore, 0.0906 mol of NH3 will produce 0.0906 x 6 = 0.0544 mol of H2O

Finally, 0.0544 mol of H2O will produce 0.0544 x 18 = 0.981g of H2O

Therefore, the mass of water produced is 0.981g

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