Answer:
H2O.....................
What is represented by the chemical formula
PbCl2(s)?
A) a substance
B) a solution
C) a homogeneous mixture
D) a heterogeneous mixture
A hemil reation
Answer:
d
Explanation:
cuaase that it sirhal
The chemical formula PbCl₂(s) represented by:
A) a substance
The chemical formula PbCl₂(s) represents a substance. A substance is a single, pure chemical entity with a definite composition. It can be an element, a compound, or an alloy.
A solution is a homogeneous mixture of two or more substances. A homogeneous mixture is a mixture in which the components are evenly distributed throughout the mixture.
A heterogeneous mixture is a mixture in which the components are not evenly distributed throughout the mixture.
A reaction is a process in which one or more substances are transformed into one or more new substances.
Therefore, the chemical formula PbCl₂(s) represents a substance, and the answer is (A).
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Which statement best describes how the tilt of Earth's rotational axis relates to the amount of solar energy received?
A. When a hemisphere is tilting away from the sun, the whole planet receives less direct sunlight,
B. When a hemisphere is tilting toward the sun, that hemisphere receives less direct sunlight.
C. When a hemisphere is tilting toward the sun, the whole planet receives less direct sunlight.
D. When a hemisphere is tilting away from the sun, that hemisphere receives less direct sunlight.
Explanation:
A. Around December 21, the Northern Hemisphere tilts the farthest away from the Sun. This is called the northern winter solstice, and it is when we have the least amount of daylight of any time of the year.
B.Solstices and shifting solar declinations are a result of Earth's 23.5° axial tilt as it orbits the sun. Throughout the year, this means that either the Northern or Southern Hemisphere is tilted toward the sun and receives the maximum intensity of the sun's rays.
C.The tilt of the Earth's axis also defines the length of daylight. Daylight hours are shortest in each hemisphere's winter. Between summer and winter solstice, the number of daylight hours decreases, and the rate of decrease is larger the higher the latitude. The fewer sunlight hours the colder the nights
D.The second solstice occurs on December 21 or 22 when the north pole is tilting 23.5 degrees away from our Sun and the south pole is inclined toward it. This is the shortest day of the year in the northern hemisphere — the northern hemisphere winter solstice.
Helppp!
Is astatine (At), atomic number 85, a metal or nonmetal? Why?
Answer:
At is a metalloid
Explanation: Meaning that it displays some of the characteristics of a metal but can also display characteristics of nonmetals. Silicon is one such element. Elemental Silicon has a dark lustrous metallic appearance but it is quite brittle. Some authorities include Astatine as a halogen as it has seven electrons in its valence shell placing it just below iodine in period 17 VIIA. Additionally, because Astatine is only ever found naturally as the result of radioactive decay from more dense elements it is the rarest naturally occurring element in Earth's crust.
I hope this helps at least a little.
Regards,
JR Holt
Chemist retired
55:28
An object is moving across a surface, but it does not gain or lose speed. Which best describes the object's force?
The net force is positive.
The net force is zero.
The positive force is greater than the negative force.
The negative force is greater than the positive force.
ke this and totum
Save and Exit
Next
S
Answer:
The correct answer is - The net force is zero.
Explanation:
When an object moves on the surface with the same or constant acceleration which means there is no gain or loss of the speed it shows that all the forces of the object are at a point of zero.
If there would be any force applied on the object there must be some change in the velocity or acceleration but in this case there is no loss or gain of speed which means there is the object's net force is zero.
Therefore, option B is correct.
In the silver recovery lab you will be doing chemical reactions and forming solid ionic compounds from their soluble ions. this question will give you practice in writing ionic compunds. What is chemical formula of the nuetral compound formed from the ions below:
1. Cr3+ ions and Cl- ions
2. Mn4+ ions and O2^- ions
3. Mg2+ ions and CO3^2- ions
Answer:
1. CrCl₃ 2. MnO₂ 3. MgCO₃
Explanation:
For a compound to be neutral, we need the same number of positive charges and negative charges.
1. Cr³⁺ ions and Cl⁻ ions. We will need 1 Cr³⁺ cation and 3 Cl⁻ anions. The chemical formula is CrCl₃.
2. Mn⁴⁺ ions and O²⁻ ions. We will need 1 Mn⁴⁺ cation and 2 O²⁻ anions. The chemical formula is MnO₂.
3. Mg²⁺ ions and CO₃²⁻ ions. We will need 1 Mg²⁺ cation and 1 CO₃²⁻ anion The chemical formula is MgCO₃.
Consider the following events that take place when rip currents occur.
A. Waves travel to the beach.
B. Waves are trapped by the sandbars.
C. Waves reach the shore and go back to the ocean.
D. Waves speed up and flow between the sandbars.
E. Waves are broken by the sandbars.
Which list shows the order of events in the production of rip currents?
Sodium azide, NaN3, the explosive compound found in automobile air bags, decomposes according to the following equation: 2NaN3(s)right arrow 2Na(s) + 3N2(g)
What mass of NaN3 is required to provide the nitrogen needed to inflate an 80.0-L bag to a pressure of 1.3 atm at 27 degree C? What is the density of the gas under these conditions?
Answer:
1.9 × 10² g NaN₃
1.5 g/L
Explanation:
Step 1: Write the balanced decomposition equation
2 NaN₃(s) ⇒ 2 Na(s) + 3 N₂(g)
Step 2: Calculate the moles of N₂ formed
N₂ occupies a 80.0 L bag at 1.3 atm and 27 °C (300 K). We will calculate the moles of N₂ using the ideal gas equation.
P × V = n × R × T
n = P × V / R × T
n = 1.3 atm × 80.0 L / (0.0821 atm.L/mol.K) × 300 K = 4.2 mol
We can also calculate the mass of nitrogen using the molar mass (M) 28.01 g/mol.
4.2 mol × 28.01 g/mol = 1.2 × 10² g
Step 3: Calculate the mass of NaN₃ needed to form 1.2 × 10² g of N₂
The mass ratio of NaN₃ to N₂ is 130.02:84.03.
1.2 × 10² g N₂ × 130.02 g NaN₃/84.03 g N₂ = 1.9 × 10² g NaN₃
Step 4: Calculate the density of N₂
We will use the following expression.
ρ = P × M / R × T
ρ = 1.3 atm × 28.01 g/mol / (0.0821 atm.L/mol.K) × 300 K = 1.5 g/L
study the reaction given below in which excess magnesium ribbon (Mg)reacts with 50cm of a diluted sulphuric acid solution at room temperature
Questions
what Changes can be made to the following substance to increase the rate of reaction?
5.1.1 Magnesium
5.1.2 Sulphuric acid
Answer:
Magnesium reacts with dilute hydrochloric acid in a conical flask which is ... One student can add the magnesium ribbon to the acid and stopper the flask, ... 50 cm3 of 1M hydrochloric acid is a six-fold excess of acid.
2. On the periodic table, what is the difference between a group (or family) and a period?
Answer:
On the periodic table,periods are horizontal rows (across) the periodic table while groups are vertical columns (down) the table.We have groups in the periodic table like transition metals,rare earth,alkali metals ,alkaline earth metals halogens and noble gases
Answer:
Horizontal row call period and vertical column called group!
Physical,chemical, reaction procedure, shape,size, enthalpy of dissociation, bonding,non bonding, various things that segregated group and period....
Which is the balanced version of the half-reaction below?
H2S → S+H+
Answer:
C. [tex]H_2S\rightarrow S+2H^++2e^-[/tex]
Explanation:
Hello there!
In this case, according to the given chemical reaction, it turns out possible to realize there is one sulfur atom on each side of the chemical equation but two hydrogen atoms on the left and one on the right, which means the latter must be balanced in agreement to the law of conservation of mass.
In such a way, by setting a 2 on H⁺, the reaction will be balanced:
[tex]H_2S\rightarrow S+2H^+[/tex]
Now, we count the transfer electrons for sulfur from -2 to 0 as 2e⁻ on the right, which will match with the option C.
[tex]H_2S\rightarrow S+2H^++2e^-[/tex]
Regards!
Compare the solubility of calcium sulfite in each of the following aqueous solutions:
a. 0.10 M Ca(CH3COO)2
b. 0.10 M K2SO3
c. 0.10 M NaNO3
d. 0.10 M KCH3COO
1. More soluble than in pure water.
2. Similar solubility as in pure water.
3. Less soluble than in pure water.
Answer:
0.10 M Ca(CH3COO)2- Less soluble than in pure water.
0.10 M K2SO3- Less soluble than in pure water.
0.10 M NaNO3 - More soluble than in pure water.
0.10 M KCH3COO- Similar solubility as in pure water.
Explanation:
We have to cast our minds back to the idea of common ions effect. If any ion is already present in solution, the presence of that ion in solution prevents any solute containing a common ion with the solution from dissolving in that solution. In order words, the presence of a common ion makes a solute less soluble in a solvent than it is in pure water.
For instance, 0.10 M Ca(CH3COO)2 and K2SO3 both contain Ca^2+ and SO3^2- ions respectively which are also contained in the solute calcium sulfite.
The presence of these common ions in solution makes calcium sulfite less soluble in these solutions than it is in pure water because the equilibrium position for the dissolution of the solute lies towards the left hand side.
However, calcium sulfite is more soluble in 0.10 M NaNO3 than in pure water due to displacement reaction between the ions in solution.
The solubility of calcium sulfite and 0.10 M KCH3COO in pure water is quite comparable.
Desclony When Fe(NO3)2 dissolves in water, what particles are present in the solution?
Answer:
hjfhgjgjgjghgjgjhgjhhjh
Atoms of element X have 12 times the mass of atoms of oxygen, and atoms of oxygen have 16 times the mass of atoms of hydrogen. What is the mass of atoms of element X on a scale on which atoms of hydrogen have a mass of 1?
A. 16/12
B. 12/16
С. 12 x 16
D. 16-12
E. 1216
Answer:
C. 12 × 16
Explanation:
Let mH be the mass of atoms of hydrogen and mO be the mass of atoms of oxygen. The atoms of oxygen have 16 times the mass of atoms of hydrogen. That is,
mO = 16 mH [1]
Let mX be the mass of the atoms of X. Atoms of element X have 12 times the mass of atoms of oxygen. That is,
mX = 12 mO [2]
If we substitute [1] in [2], we get
mX = 12 × 16 mH
If mH is 1, we get,
mX = 12 × 16 × 1
mX = 12 × 16
A weather balloon containing helium with a volume of 410.0 L rises in the atmosphere and is cooled from 17∘
∘
C to -27∘
∘
C. The pressure on the gas is reduced from 110.0 kPa to 25.0 kPa. What is the volume of the gas at the lower temperature and pressure? What law did you use to solve?
Answer:
V₂ = 1500 Liters ( 2 sig. figs.)
Explanation:
Given the following gas law variables:
P₁ = 110.0KPa P₂ = 25KPa
V₁ = 410 Liters V₂ = ?
T₁ = 17°C ( = 290K) T₂ = -27°C ( = 248K)
P₁V₁/₁T₁ = P₂V₂/T₂ => V₂ = V₁(P₁/P₂)(T₂/T₂)
V₂ = 410L(110.0KPa/25KPa)(248k/290K) = 1542 L (calc. ans.)
V₂ = 1500 Liters ( 2 sig. figs.)
Match all the terms that apply to each element. Some terms may apply to more than one element.
a. Main group element
b. halogen
c. noble gas
d. inner transition element
e. alkaline earth
f. Non-metal
g. Alkali metal
h. Metalloid
i. Metal
1. Titanium
2. Gold
3. Argon
4. Thallium
Answer:
Titanium - Metal
Gold - Metal
Argon - noble gas
Thallium - Metal
Explanation:
A metal is a species that easily looses electrons to yield a positive ion. Metals are found in the left hand side of the periodic table.
Thallium is a groups 13 metal, gold is a group 11 metal while titanium is a 4 metal.
However, argon is a noble gas hence it belongs to groups 18 of the periodic table.
Titanium -metal
gold - metal,
Argon - noble gas
Thallium -metal, transition metal
Explanation:
In modern periodic table :
Metals are listed from the middle to left-hand side of the periodic tableNonmetals are listed on the upper right-hand side of the periodic tableMetalloids divide the periodic table in a zig-zag line with nonmetals on the right and metals on the left.The alkali metals are listed under group 1The alkaline earth metals are listed under group 2The noble gases are listed under group 18The transition metals are listed from group 3 to group 12.The halogens are listed under group 17The inner transition elements (f-block) are listed at the bottom separately.So, from this, we can match the given elements as:
Titanium -metal
gold - metal,
Argon - noble gas
Thallium -metal. transition metal
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Select the keyword or phrase that will best complete each sentence about the three general rules of for drawing Lewis structures.a. main group b. hafnium c. valence d. hydrogen e. core f. transition metal1. Draw only__the electrons. 2. Give every___element (except hydrogen) an octet of electrons. 3. Give each____two electrons.
Answer:
1. Draw only the valence electrons.
2. Give every element main group element (except hydrogen) an octet of electrons.
3. Give each hydrogen two electrons.
Explanation:
Lewis structures are used to describe the arrangement or configurations of the valence electrons of molecules and polyatomic ions involved in electronic bonding. A Lewis structure consists of the symbols of the elements in the molecule surrounded by dots with each dot representing each of the elements valence electrons. Also, the electrons shared between two elements are shown by dots between the two elements and these electrons are known as shared electron pairs. The valence electrons on atom that is not involved in bonding is known as lone pairs.
The three general rules for drawing Lewis structures are:
1. Draw only the valence electrons. Only the valence electrons of the atoms of elements are shown since they are the only electrons involved in chemical bonding.
2. Give every element main group element (except hydrogen) an octet of electrons. The complete eight valence electrons of the noble gases is associated with their stability. Thus, the main group elements show a tendency to form enough bonds to obtain eight valence electronsmin order to achieve stability. This is known as the octet rule. However, since the maximum number of valence electrons for elements in the first period of the period table is two, the noble gas helium has completely-filled valence shell containing two electrons known as a duplet. Hydrogen belongs to the first period and is therefore an exception tomthe octet rule.
3. Give each hydrogen two electrons. Hydrogen attains a duplet structure in accordance with the structure of helium
How many grams of KNO3 can dissolve in 100g of water at 20°C?
Answer:
30 grams of KNO3 can be dissolved.
Explanation:
Hello there!
In this case, since the solubility is defined as the maximum amount of solute that can be dissolved in a certain amount of solvent, usually 100 grams of water as function of the temperature, we will need to recall the graph for the solubility of KNO3 as shown on the attached file.
Thus, by identifying the curve for KNO3, we realize that at a temperature of 20 °C, the solubility is about 30 grams; which means 30 grams can be dissolved in 100 grams of water at 20 °C.
Regards!
Which of the following is not generally a characteristic of metal?
Ductility
O
Malleability
High melting point
Low boiling point
An ideal gas is made up of gas particles that...
(A) ...have volume.
(B) ... attract each other.
(C)...can be liquified.
(D) ... are in random motion.
Answer:
Its D Are in random motion
i hope it will help you if not soo sorry :)
Consider the following electron configurations to answer the questions that follow: (i) 1s2 2s2 2p6 3s1 (ii) 1s2 2s2 2p6 3s2 (iii) 1s2 2s2 2p6 3s2 3p1 (iv) 1s2 2s2 2p6 3s2 3p4 (v) 1s2 2s2 2p6 3s2 3p5 The electron configuration belonging to the atom with the highest second ionization energy is ________.
Option (i) would have the highest 2nd Ionization Energy.
Option (i) is Sodium.
Can be Written as 2, 8 , 1
For its 1st Ionization energy... It'd be extremely easy to remove that Electron cos its on the outermost shell.
Now After Removing that Electron...
Sodium's Electronic Configuration Reduces to that of Neon Which is 2, 8.
Neon has a very stable Octet.
It would take an ENORMOUS amount of energy to break its Octet stability... that is... Remove 1 electron from its Octet.
So
Option (i) [Sodium] has the highest 2nd Ionization Energy
In an oxidation-reduction reaction, the substance oxidized always ________. a. takes on oxygen atoms b. gives up hydrogen atoms c. gains electrons d. loses electrons e. becomes a charged species
Answer:
Explanation:
Let us define oxidation and reduction.
Oxidation and reduction deal with the transferring of electrons between reactants. The reactant that loses electrons is oxidized, while the reactant that gains electrons is reduced.
In an oxidation-reduction reaction, the substance oxidized always loses electrons and the correct option is option D.
An oxidation-reduction (redox) reaction is a type of chemical reaction that involves the transfer of electrons between species. It consists of two half-reactions: an oxidation half-reaction, where a species loses electrons and increases its oxidation state, and a reduction half-reaction, where a species gains electrons and decreases its oxidation state.
In an oxidation half-reaction, the species that is oxidized is called the reducing agent or the electron donor, as it donates electrons. In a reduction half-reaction, the species that is reduced is called the oxidizing agent or the electron acceptor, as it accepts electrons.
Thus, the ideal selection is option D.
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Convert 400.0 ng/dL to cg/L
Answer:
.04 cg/L
Explanation:
Anew fictitious element was discovered. It is a metal named jolmium, J,and it has three valence electrons. If it combineswith iodine it forms jolmium iodide. Answer the following questions.a.Is this compound ionic or covalent
a. Is this compound ionic or covalent?
b. What is the formula of Jolmium iodide?
c. What is the charge on the metal J in this compound?
d. Explain how you know that is the charge?
Answer:
A new fictitious element was discovered.
It is a metal named jolmium, J, and it has three valence electrons.
If it combines with iodine it forms jolmium iodide. Answer the following questions.
a.Is this compound ionic or covalent
b. What is the formula of Jolmium iodide?
c. What is the charge on the metal J in this compound?
d. Explain how you know that is the charge?
Explanation:
It is given the element jolmium J is a metal with three valence electrons.
Since metals are highly electropositive, they lose electrons easily and form cations (Ions with a positive charge).
[tex]J^{3+}[/tex] ion will be formed.
b) The formula of jolmium iodide is shown below:
[tex]J^{+3} I^{-1}\\The formula becomes:\\JI_{3}[/tex]
a) The compound is ionic in nature.
Since the compound formed between a metal atom and a nonmetal atom will take place by transfer of electrons.
Hence, it is ionic in nature.
c) The charge on the metal J in this compound is +3.
d) Given J has three valence electrons.
That means it can lose three electrons to form a bond.
So, its valency is three.
A stain is made up of molecules that do not have charged regions. What soap/solvent combination should I use?Are there multiple?
Answer:
The answer is below
Explanation:
Yes, there are multiple combinations.
Firstly, a solvent or soap combination could be used as a polar solvent with soap. In this way, the nonpolar region of the soap molecules would mix directly with the stain while the solvent would surround the soap-stain micelle.
Secondly, another method or way is to have a combination of a nonpolar solvent with no soap. In this method, however, it is the solvent that would mix directly with the stain.
How many grams of solid sodium cyanide should be added to 1.00 L of a 0.119 M hydrocyanic acid solution to prepare a buffer with a pH of 8.809
Answer:
1.62 g
Explanation:
Given that:
Concentration of HCN = 0.119 M
Assuming the ka 4.00 × 10⁻¹⁰
The pKa of HCN (hydrocyanic acid) = -log (Ka)
= - log ( 4.00 × 10⁻¹⁰)
= 9.398
pH of buffer = 8.809
Using Henderson Hasselbach equation:
[tex]pH = pKa + log \dfrac{[conjugate\ base ]}{acid}[/tex]
[tex]pH = pKa + log \dfrac{[CN^-]}{[HCN]}[/tex]
[tex]8.809 = 9.398 +log \dfrac{[CN^-]}{[HCN]}[/tex]
[tex]log \dfrac{[CN^-]}{[HCN]}= 8.809 - 9.398[/tex]
[tex]log \dfrac{[CN^-]}{[HCN]}= -0.589[/tex]
[tex]\dfrac{[CN^-]}{[HCN]}= 0.2576[/tex]
[CN^-] = 0.2576[HCN]
[CN^-] = 0.2756 (0.119) L
[CN^-] = 0.033 M
∴
The amount of NaCN (sodium cyanide) is calculated as follows:
[tex]= 1.00 L \times \dfrac{0.033 \ mol \ NacN }{1 \ L } \times \dfrac{49.01 \ g}{1 \ mol \ of \ NacN}[/tex]
= 1.62 g
carbon dioxide gas evolve during the fermentation of sugar which was collected at 22.5°C and 0.945 ATM after perfect strangers in the volume was found to be 25.0 ML how many grams of carbon dioxide were collected
Answer:
0.043 grams
Explanation:
We can find the mass of carbon dioxide as follows:
[tex] m = n*M [/tex]
Where:
n: is the number of moles
M: is the molar mass = 44.01 g/mol
First, we need to calculate the number of moles. We can use the Ideal gas equation:
[tex] PV = nRT [/tex]
Where:
P: is the pressure = 0.945 atm
V: is the volume = 25.0 mL
R: is the gas constant = 0.082 L*atm/(K*mol)
T: is the tempearture = 22.5 °C
[tex]n = \frac{PV}{RT} = \frac{0.945 atm*25 mL*\frac{1 L}{1000 mL}}{0.082 L*atm/K*mol*(22.5 + 273) K} = 9.75 \cdot 10^{-4} moles[/tex]
Hence, the mass is:
[tex]m = 9.75 \cdot 10^{-4} moles*44.01 g/mol = 0.043 g[/tex]
Therefore, 0.043 grams were collected.
I hope it helps you!
The half life for the radioactive decay of potassium-40 to argon-40 is 1.26×109 years. Suppose nuclear chemical analysis shows that there is 0.359 mmol of argon-40 for every 1.000mmol of potassium-40 in a sample of rock. Calculate the age of the rock.
Answer:
2.42x10⁹ years is the age of the rock
Explanation:
The decay of an isotope follows the equation:
Ln[A] = -kt + Ln[A]₀
Where [A] is amount of isotope after time t, k is decay constant and [A]₀ is the initial amount of the isotope
To find decay constant from half-life:
k = ln2 / half-life
k = ln2 / 1.26x10⁹years
k = 5.501x10⁻¹⁰ years⁻¹
As in the reaction, K-40 produce Ar-40:
[A] = 0.359mmol
[A]₀ = 0.359mmol + 1.000mmol = 1.359mmol
Replacing:
Ln[0.359mmol] = -5.501x10⁻¹⁰ years⁻¹t + Ln[1.359mmol]
-1.3312 = -5.501x10⁻¹⁰ years⁻¹t
t = 2.42x10⁹ years is the age of the rock
Which of the following expressions is the correct equilibrium constant expression for the equilibrium between dinitrogen tetroxide and nitrogen dioxide? N subscript 2 O subscript 4 space left parenthesis g right parenthesis space rightwards arrow over leftwards arrow 2 space NO subscript 2 space left parenthesis straight g right parenthesis
Answer:
Correct answer:
The equilibrium expression is defined as the ratio of the concentration of products divided by the concentration of the reactants. Each reactant or product is raised to the power corresponding to its coefficient in the balanced chemical equation.
Explanation:
After mixing the solutions in a separatory funnel, the stopper should be ______ and the liquid should be _______ and the layers allowed to separate. When you get close to the interface between the layers, ______ the funnel and turn over _______ heat up until the first layer is collected get eye level with to collect the second layer. _______
Answer:
Hence,
1) removed
2) drained through the stopcock
3) get eye level with
4) slow the draining
5) switch to a new flask
Explanation:
After mixing the solutions in a separatory funnel, the stopper should be removed and the liquid should be drained through the stopcock, and the layers allowed to separate. When you get close to the interface between the layers, get eye level with the funnel and turn over to slow the draining heat up until the first layer is collected. Switch to a new flask get eye level with it to collect the second layer.
A chemistry student needs 15.0 g of methanol for an experiment. She has available 320. g of 44.4% w/w solution of methanol in water. Calculate the mass of solution the student should use. If there's not enough solution, press the "No solution" button. Round your answer to 3 significant digits.
Answer:
33.8 g Solution
Explanation:
A chemistry student needs 15.0 g of methanol for an experiment. The concentration of ethanol in the solution is 44.4% w/w, that is, there are 44.4 g of methanol every 100 g of solution. The mass of solution that would contain 15.0 g of methanol is:
15.0 g Methanol × 100 g Solution/44.4 g Methanol = 33.8 g Solution
Since 33.8 g are required and 320. g are available, there is enough solution for the requirements.