Please help
6.0 mol Al reacts with 4.0 mol O2 to
form Al2O3.
4AI + 302 → 2Al2O3
How many moles of Al2O3 form when
4.0 mol O2 reacts?
[?] mol Al2O3

The mass of solid is 76.905 g.

Given that,

Total volume of solid and liquid = 81.0 mL

Mass of liquid = 40.5 g

Density of liquid = 0.865 g/mL

Density of solid = 2..25 g/mL

We need to calculate the volume of liquid

Using formula of density

[tex]Density = Mass/volume(V_{l} } )\\\\volume(V_{l} )=Mass/Density[/tex]

Put the value into the formula

[tex]V_{l} = 40.5/0.865\\\\V_{l} = 46.82 mL[/tex]

We need to calculate the volume of solid

Volume of solid = Total volume of solid and liquid- volume of liquid

[tex]V_{s} =81.0-46.82\\\\V_{s} =34.18 mL[/tex]

We need to calculate the mass of solid

[tex]P_{s}=M_{s} /V_{s} \\\\M_{s} =P_{s}V_{s}[/tex]

Using formula of density

Put the value into the formula

[tex]M_{s}=2.25 X 34.18\\\\M_{s}=76.905 g[/tex]

Hence, The mass of solid is 76.905 g.

A substance's density (more accurately, its volumetric mass density; sometimes known as specific mass) is its mass per unit volume. The most common symbol for density is (the lower case Greek letter rho).

There are three types of Density:

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Answer:

12.5 mL NH₃

Explanation:

To find the volume of NH₃, you need to (1) find the moles (NH₄)₂PtCl₄ (using the molarity equation), then (2) convert moles (NH₄)₂PtCl₄ to moles NH₃ (via mole-to-mole ratio from balanced equation, and then (3) find the volume NH₃ (using the molarity equation).

(Step 1)

25.00 mL / 1,000 = 0.025 L

Molarity = moles / volume (L)

0.100 M = moles / 0.025 L

0.0025 = moles (NH₄)₂PtCl₄

(Step 2)

The unbalanced equation:

(NH₄)₂PtCl₄ + NH₃ ----> Pt(NH₃)₂Cl₂ + NH₄Cl

Reactants: 2 nitrogen, 11 hydrogen, 1 platinum, 4 chlorine

Products: 2 nitrogen, 10 hydrogen, 1 platinum, 3 chlorine

The balanced equation:

(NH₄)₂PtCl₄ + 2 NH₃ ----> Pt(NH₃)₂Cl₂ + 2 NH₄Cl

Reactants: 3 nitrogen, 14 hydrogen, 1 platinum, 4 chlorine

Products: 2 nitrogen, 14 hydrogen, 1 platinum, 4 chlorine

0.0025 moles (NH₄)₂PtCl₄              2 moles NH₃
----------------------------------------  x  ------------------------------  =  0.0050 moles NH₃
                                                      1 mole (NH₄)₂PtCl₄

(Step 3)

Molarity = moles / volume (L)

0.400 M = 0.0050 moles / volume

(0.400 M) x volume = 0.0050 moles

volume = 0.0125 L NH₃

0.0125 L x 1,000 = 12.5 mL NH₃

Answer:

1. Mixture

2. Compound

3. Compound

4. Element

Explanation:

Number 1 shows two completely different types of compounds in the same space, so it is a mixture.

Numbers 2 and 3 are compounds because there aren't different types compounds as in Number 1, but the same compound repeated. 2 is a compound because while all of the circles are the same element, they are connected. O2 for example, oxygen, is a compound.

Number 4, finally, is all of the same substance, non-connected, so it shows an element.

Brainliest, please :) (Trying to become a genius so that I can continue helping more people)

Answer:

28.1 moles   (three sig digits)

Explanation:

Using Ideal Gas Law

PV = n RT      looking for 'n'   R = .082057366  L-atm/K-mole

15.0 * 45.0  = n  * .082057366 * 293

n = 28.1 Moles

The number of moles of helium that are in a 45.0-liter tank at 293 K and 15.0 atm is  28.1 Moles.

Moles is the measuring unit that measures the quantity of a substance. Moles is a SI unit.

Helium is the lightest gas, which is used in the tires of an airplane if it is filled in the balloons, the balloon flies in the sky.

Given the volume is 45.0 liter

The pressure is 15.0 atm.

The temperature is 293 K

To calculate the moles, we will use the formula of an ideal gas:

PV = n RT      

R = .082057366 is the gas constant.

We have to calculate the n

Putting the values in the equation

15.0 x 45.0  = n  x .082057366 x 293

n = 28.1 Moles.

Thus, the moles of helium is n = 28.1 Moles.

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The element with the lowest melting point is Ga.
Hence, Option (C) is correct answer.

Melting point is usually defined as the temperature at which solid changes to liquid.

The melting point order of B, Al, Ga, Tl is B > Al> Tl > Ga due to structural changes, melting point increases from Ga to Tl. Hence Ga has the lowest melting point among all these.

Thus from the above conclusion we can say that The element with the lowest melting point is Ga.
Hence, Option (C) is correct answer.

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NO is a stable compound

The octet rule describes an atom's propensity to favor eight electrons in its valence shell. Atoms with fewer than eight electrons are more likely to interact with one another and create a more stable compound.

The majority of other odd-electron molecules, including NO, are highly chemically reactive and stable compounds. The second breach of the octet rule is the presence of molecules lacking electrons. Less than eight electrons are positioned around each atom in these stable compounds.

The overall molecular orbital arrangement of NO will be as follows, nitrogen has 7 electrons and oxygen has 8 electrons, according to the molecular orbital theory.

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Answer:

1,69 x10²⁴

Explanation:

Answered it in the comments! ^^

The coordination number shows the number of ligands attached to the central metal.

The coordination number and the charge on the central metal in each of the complexes are shown below;

Na2[Zn(OH)4] - The coordination number of the complex is 4 and the charge on the central metal ion is +2.

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Answer:

nuetral

Explanation:

water has neutral

Bonding gels and gel primers are designed specifically to improve adhesion of light cured gels to the natural nail plate and is therefore denoted as option C.

This is defined as the tendency of particles or substance which have dissimilar origins to stick to one another. A common adhesive is referred to as glue, cement etc  and ensures there is enough resistance for their separation in case of the presence of any type of external force or stimuli acting on them.

Gel primer is referred to a vital used in makeup and serves as a form of foundation before they are applied on the skin of individuals so as to enable it stick and also look more presentable.

This is therefore the reason why gel primers was chosen as the most appropriate choice.

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Ka value of monoprotic weak acid:

The experimental ka value of this acid is 6.3 × [tex]10^{-5}[/tex]  

Half-equivalence point:  

At half equivalence point, pH = pKₐ

The pKa is determined by the weak acid's Ka acid dissociation constant.

pKₐ = -log(Kₐ)

Kₐ = [tex]10^{-pKa}[/tex]

At the half equivalence point,

Kₐ = [tex]10^{-pH}[/tex]

Given,

pH = 4.20. By putting the value;

Kₐ = [tex]10^{-4.20}[/tex]

     = 6.3 × [tex]10^{-5}[/tex]  

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Answer:

it's both impossible and inefficient

Explanation:

think about it, if your spatula can even fit in the bottle will it take out a measured amount of powder? if the spatula has holes in it the powder will fall out and you will have to restart the experiment

Answer:

[tex]10^{-6} \frac{mol}{L}[/tex]

Explanation:

Comparing to the solution consisting a pH of 5 containing [tex]10^{-5}[/tex]  [tex]\frac{mol}{L}[/tex] of hydrogen ions, a solution having a pH of 6 consists of [tex]10^{-6} \frac{mol}{L}[/tex] of hydrogen ions. A solution having a pH of 7 too will have a pH of [tex]10^{-7} \frac{mol}{L}[/tex].

From the mole ratio CO₂ and CS₂ in the reaction, the moles of CO₂ produced is 0.109 moles.

The mole ratio of the reaction is the ratio in which the reactants combine to form products.

The mole ratio of the reaction is obtained from the equation of the reaction.

The equation of the reaction is given below:

Mole ratio of CO₂ and CS₂ is 1 : 1

Moles of CS₂ reacting = mass/molar mass

Molar mass of CS₂ is 76 g/mol

Mass of CS₂ reacting is 8.28 g

Moles of CS₂ reacting = 8.28/76

Moles of CS₂ reacting = 0.109 moles

Based on the mole ratio of the reaction, moles of CO₂ produced is 0.109 moles.

In conclusion, the moles of CO₂ produced is determined from the mole ratio CO₂ and CS₂ in the reaction.

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Answer:

Explanation:

The best way to change Celsius to Fahrenheit is to times it by 1.8 then plus 32

If the same test, given at different points in time to the same test takers, yields different scores, then the method typically used to assess this source of error is alternate form.

An alternate form or parallel form test is a test which is conducted at different time on the same set of test takers in order to test the reliability of the results obtained.

In conclusion, alternate or parallel form tests is a test of reliability.

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The name of pb(no3)2 is Lead(II) nitrate.

pb(no3)2 is an ionic compound.

How to name ionic compound?

Name of pb(no3)2:

The charge of nitrate ion NO3 is -1. To find the charge of lead, we'll take it as x. Hence,

x+2(-1)=0

x=2

The charge of lead cation in this ionic compound is calculated as +2.

Therefore the name of pb(no3)2 is confirmed as Lead(II) Nitrate.

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The statements which describe some of the original ideas proposed about the universe during the big bang include:

This theory describes how the universe expanded from a single point to form the earth we are living in.

it states that the very dense and hot environment led to it thereby making it the most appropriate choice.

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D. The concentration for the B mixture is 0.5 M.

kc = [B]/[A]

where;

B = kc(A)

B = (5x 10²)(1 x 10⁻³)

B = 0.5 M

Thus, the concentration for the B mixture is 0.5 M.

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In a voltaic cell, a salt bridge is needed to allow the motion of ions between the terminals. In the salt bridge, anions move toward the anode and cations move toward the cathode.

A voltaic cell is an electrochemical device that harnesses the power of a chemical process to generate electrical energy. A voltaic cell's key components are:

When an electrode is dipped into the electrolyte at the electrode and electrolyte contact surface in a voltaic cell, the electrode's atoms tend to produce positive ions in the electrolytic solution while leaving the electrode's electrons unaffected. The electrode thus acquires a negative charge.

Additionally, the electrolytic solution's positive ions have a propensity to deposit on the electrode, giving it a positive charge. The electrodes get positively or negatively charged in relation to the electrolyte as a result of the two opposite processes. As a result, there is a potential difference between the electrode and electrolyte. The term "electrode potential" refers to this potential difference.

Now, the electrode where reduction occurs is known as the cathode and turns positive in relation to the electrolytic solution, whereas the electrode where oxidation occurs is known as the anode and has a negative potential in relation to the electrolytic solution. This caused a potential difference to form between the voltaic cell's two electrodes. Cell Potential is the name given to this potential differential.

The voltaic cell's potential is sometimes referred to as its electromotive force (EMF) when no current is being drawn from it. Electrons begin to flow from the anode (negative electrode) to the cathode when an external circuit is connected to the voltaic cell (positive electrode). As a result, in the external circuit, the normal current flows from the positive terminal to the negative terminal.

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The labels required by the Department of Transportation (DOT) must be placed on outside containers when chemicals are being shipped.

These labels may look similar to GHS pictograms and categorize hazardous chemicals into nine different categories.

OSHA recently revised the Hazard Communication Standard, and as part of that modification, new standards for labeling dangerous chemicals were established.

As a result, workers will have better information available on the safe handling and use of hazardous chemicals, thereby allowing them to avoid injuries and illnesses related to exposures to hazardous chemicals.

These modifications will aid in ensuring higher standards and uniformity in the categorization and labeling of all substances.

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The main constituent of gallstones is cholesterol. Cholesterol may have a role in heart attacks and blood clot formation. Its elemental percentage composition is 83.87% C, 11.99% H, and 4.14% O. It has a molecular weight of 386.64 amu. Empirical formula is C₃H₄O₁ and Molecular formula is 7(C₃H₄O₁).

Empirical formula is the simplest whole number ratio of atoms present in given compound.

Element   %   Atomic mass   Relative no. of atoms  Simplest whole ratio

C            83.87       12                     [tex]\frac{83.87}{12}[/tex] = 6.98                   [tex]\frac{6.98}{0.25}[/tex] = 3

H            11.99         1                       [tex]\frac{11.99}{1}[/tex] = 11.09                  [tex]\frac{11.09}{0.25}[/tex] = 4

O            4.14          16                      [tex]\frac{4.14}{16}[/tex] = 0.25                    [tex]\frac{0.25}{0.25}[/tex] = 1

Thus the empirical formula is C₃H₄O₁.

Molecular formula = Empirical formula × n

n = [tex]\frac{\text{Molecular weight}}{\text{Empirical formula weight}}[/tex]

  = [tex]\frac{386.64}{56}[/tex]

  = 7

Molecular formula = Empirical formula × n

                               = 7 (C₃H₄O₁)

Thus from the above conclusion we can say that The main constituent of gallstones is cholesterol. Cholesterol may have a role in heart attacks and blood clot formation. Its elemental percentage composition is 83.87% C, 11.99% H, and 4.14% O. It has a molecular weight of 386.64 amu. Empirical formula is C₃H₄O₁ and Molecular formula is 7(C₃H₄O₁).

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Answer:

Fe(CH₂CO₂)₂, Fe₂MnO, Pb(CH₂CO₂)₄, PbMnO

Explanation:

Cations (positively charged ions) can only form ionic bonds with anions (negatively charged ions). However, you can't just simply put one cation and one anion together to form a compound. Each compound needs to been neutral, or have an overall charge of 0. When cations and anions do not have charges that perfectly cancel, you need to modify the amount of each ion in the compound.

1.) Fe(CH₂CO₂)₂

   ----> Fe²⁺ and 2 CH₂CO₂⁻

   ----> +2 + (-1) + (-1) = 0

2.) Fe₂MnO

   ----> 2 Fe²⁺ and 1 MnO⁴⁻
   ----> 2(+2) + (-4) = 0

3.) Pb(CH₂CO₂)₄
   ----> 1 Pb⁴⁺ and 4 CH₂CO₂⁻
   ----> +4 + (-1) + (-1) + (-1) + (-1) = 0

4.) PbMnO

   ----> 1 Pb⁴⁺ and 1 MnO⁴⁻

   ----> +4 + (-4) = 0

Answer:

Limiting Reagent: NaHCO₃

Amount of NaCl: 69.6 g NaCl

Mass of Excess Reagent: 56.6 g HCl

Explanation:

To find the mass of NaCl, you need to (1) convert mass reactant to moles reactant (via molar mass), then (2) convert moles reactant to moles NaCl (via mole-to-mole ratio from equation coefficients), and then (3) convert moles NaCl to mass NaCl (via molar mass).

Molar Mass (NaHCO₃):

22.990 g/mol + 1.008 g/mol + 12.011 g/mol + 3(15.998 g/mol)

Molar Mass (NaHCO₃): 84.003 g/mol

Molar Mass (HCl): 1.008 g/mol + 35.453 g/mol

Molar Mass (HCl): 36.461 g/mol

Molar Mass (NaCl): 22.990 g/mol + 35.453 g/mol

Molar Mass (NaCl): 58.443 g/mol

100 g NaHCO₃            1 mole                  1 mole NaCl             58.443 g
------------------------  x  ------------------  x  ---------------------------  x  ----------------  =
                                   84.003 g            1 mole NaHCO₃            1 mole

=  69.6 g NaCl

100 g HCl            1 mole               1 mole NaCl          58.443 g
----------------  x  ------------------  x  -----------------------  x  ----------------  =
                           36.461 g             1 mole HCl              1 mole

=  160 g NaCl

Since NaHCO₃ results in the smaller amount of product, it is the limiting reagent. In other words, it is used up before the HCl has the chance to completely react. Therefore, the actual amount of NaCl produced is 69.6 grams.

To find the mass of the excess reagent, you need to calculate the amount of HCl actually used in the reaction. Then, you need to subtract that value from the total amount of HCl.

69.6 g NaCl             1 mole                1 mole HCl             36.461 g
---------------------  x  ------------------  x  -----------------------  x  ----------------  =
                                58.443 g            1 mole NaCl             1 mole

=  43.4 g HCl

Amount Given - Amount Reacted = Mass Excess

100 g HCl - 43.4 g HCl = 56.6 g HCl

Answer:

There are millions of organic compounds but only thousands of inorganic compounds because:

a. organic compounds were formed by living things.

b. there is more carbon on Earth's surface than any other element.

c. atoms of elements other than carbon never combine with themselves.

d. carbon atoms can combine with up to four other atoms, including other carbon atoms.

This causes organic matter to decompose faster, releasing larger amounts of carbon dioxide into the atmosphere

As a result of climate change, tundra soils are thawing deeper and deeper and for a longer time in the upper layers of surface.

The tundra is a biome on the Earth that covers approximately 20% of its land mass, and it is almost exclusively located in the Northern Hemisphere.

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Answer:

positron

Explanation:

PET scanning works by injecting a radioactive material, called a tracer, into the body. The tracer emits a positron inside the body, and the positron collides with electrons in the body, thereby annihilating and releasing two gamma rays that travel in opposite directions.

Substances in order of increasing vapor pressure at a given temperature is SF4 < SF6 < SiH4

Which has highest vapor pressure?

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