CHEMH1 FINAL 2025

What SI unit is used to measure the number of representative particles in a substance?

mole

Which of the following elements exists as a diatomic molecule?

nitrogen

The mass of a mole of NaCl is the

molar mass

What is the molar mass of (NH4)2CO3?

96g

The molar volume of a gas at STP occupies ____.

22.4 L

Chemical equations must be balanced to satisfy

the law of conservation of mass.

In a chemical reaction, the mass of the products

is equal to the mass of the reactants.

What is the first step in most stoichiometry problems?

convert given quantities to moles

Which type of stoichiometric calculation does not require the use of the molar mass?

volume-volume problems

Why is a gas easier to compress than a liquid or a solid?

The volume of a gas's particles is small compared to the overall volume of the gas.

Why does the pressure inside a container of gas increase if more gas is added to the container?

There is an increase in the number of collisions between particles and the walls of the container.

If a balloon is squeezed, what happens to the pressure of the gas inside the balloon?

it increases.

What happens to the temperature of a gas when it is compressed?

the temperature increases.

What happens to the pressure of a gas inside a container if the temperature of the gas decreases?

The pressure decreases.

Why does air escape from a tire when the tire valve is opened?

The pressure outside the tire is lower than the pressure inside the tire.

Which of these changes would cause a decrease in the pressure of a contained gas?

The volume of the container is increased.

When the Kelvin temperature of an enclosed gas doubles, the particles of the gas

move faster

The volume of a gas is doubled while the temperature is held constant. How does the gas pressure change?

it is reduced by one half.

The volume of a gas is reduced from 4.0 L to 0.5 L while the temperature is held constant. How does the gas pressure change?

it increases by a factor of 8.

If a balloon is heated, what happens to the pressure of the air inside the balloon if the volume remains constant?

it increases

If a sealed syringe is plunged into cold water, in which direction will the syringe piston slide?

in

A 10-g mass of krypton occupies 15.0 L at a pressure of 210 kPa. Find the volume of the krypton when the pressure is increased to 790 kPa.

4.0L

A gas has a pressure of 710 kPa at 227C. What will its pressure be at 27C, if the volume does not change?

426 kPa

What is one standard atmosphere of pressure in kilopascals?

101.3 kPa

What is the SI unit of pressure?

pascal

How does the surface tension of water compare with the surface tensions of most other liquids?

it is higher

What causes water's low vapor pressure?

hydrogen bonding

What is the shape of the water molecule?

bent

Which of the following is primarily responsible for holding water molecules together in the liquid state?

hydrogen bonds

Which atom in a water molecule has the greatest electronegativity?

the oxygen atom

The bonds between adjacent water molecules are called ____.

hydrogen bonds

What is primarily responsible for the surface tension of water?

hydrogen bonding

Which of the following is one of the effects of the high surface tension of water?

Water has an unusually low vapor pressure.

Which of these is a correct observation about surface tension?

It is the inward force which tends to minimize the surface area of a liquid.

The bonds between the hydrogen and oxygen atoms in a water molecule are ____.

polar covalent bonds

Which is responsible for the high thermal energy required to melt ice?

hydrogen bonding

Which of the following substances is the most soluble in water?

sodium chloride

What occurs in solvation?

Solvent molecules surround solute ions.

Why is a nonpolar substance able to dissolve a different nonpolar substance?

They have similar attractive forces in their molecules.

An electric current can be best conducted by ____.

a salt solution

The fact that ice is less dense than water is related to the fact that ____.

ice has a molecular structure that is an open framework held together by hydrogen bonds

Which of the following usually makes a substance dissolve faster in a solvent?

agitating the solution

How does shaking or stirring a mixture of solute and solvent affect a solution?

It increases the rate of dissolving.

Which of the following factors affect solubility?

temperature and the nature of the solvent

If adding of a crystal of the solute to an aqueous solution causes many particles to come out of the solution, the original solution was ____.

supersaturated

Which of the following generally occurs as temperature increases?

Solubility of a solid solute increases.

Which phrase correctly describes the effect of pressure on the solubility of a gas in a liquid?

directly proportional to the pressure of the gas above the liquid

What happens to the solubility of a gas in a liquid if the partial pressure of the gas above the liquid decreases?

the solubility decreases

What is the concentration of a solution?

a measure of the amount of solute in a specified quantity of solvent

What measures are used to calculate the percent by volume of a solution?

volume of solute and volume of solution

Which of the following is a colligative property of a solution?

boiling point elevation

Colligative properties depend upon the ____

number of solute particles in a solution.

A solute depresses the freezing point because the solute ____

disrupts crystal formation of the solvent.

What SI unit is used to measure the number of representative particles in a substance?

mole

The mass of a mole of NaCl is the

molar mass

Which of the following is unchanged when a solution is diluted by the addition of solvent?

number of moles of solute