chem final version B

What is the calculation of quantities in chemical reactions called?

Stoichiometry

In the reaction 2H₂ + O₂ → 2H₂O, what is the mole ratio of oxygen to water?

1:2

What remains constant in a balanced chemical equation?

The total mass of reactants and products

What is the reactant that remains after a reaction stops called?

Excess reagent

How many atoms are in 1.0 moles of MgO?

1.20 × 10²⁴ atoms

What does actual yield divided by theoretical yield, multiplied by 100, give?

Percent Yield

Which unit is used to express the concentration of a solution?

Molarity (M)

What is the molar mass of Mg(OH)₂?

58 g/mol

To convert from moles of Substance A to moles of Substance B, what must you use?

The coefficients from the balanced equation

What do you perform when you add more solvent to a solution?

Dilution

Which variable is NOT one of the four used to describe a gas?

Density (D)

How do you convert a Celsius temperature to Kelvin?

Add 273

Which gas law is used when the number of moles (n) is constant and P, V, and T all change?

Combined Gas Law

According to Charles's Law, at constant pressure, temperature is what?

Directly proportional to volume.

What is gas pressure the result of?

Particles colliding with an object.

Which gas law focuses on the rate of gas escaping through a small hole?

Graham's Law

In a mixture of gases, what is the total pressure?

The sum of the partial pressures.

When using gas laws, what unit must temperature be in?

Kelvin

As the volume of a gas decreases at a constant temperature, what happens to the pressure?

Increases

Why are gases easily compressed?

Because of the empty space between molecules.

Why does a powdered solid reactant increase the reaction rate?

It increases the surface area available for collisions.

On a potential energy diagram, what is the difference between the energy of the reactants and the peak of the curve?

Activation Energy (Eₐ)

If a reaction is 'zero order' with respect to a reactant, what happens when you double its concentration?

Have no effect on the rate.

What does a reaction mechanism consist of?

A series of elementary steps that lead to the final product.

What is the 'Rate-Determining Step' in a mechanism?

The slowest step.

Which state of matter has the lowest entropy?

Solid

In the equilibrium PCl₅(g) + Heat ⇌ PCl₃(g) + Cl₂(g), what happens when you add more Cl₂(g)?

Shift the equilibrium to the left.

According to Le Châtelier's Principle, what happens if you decrease the volume of a gas system?

The equilibrium shifts toward the side with fewer moles of gas.

What does Gibbs Free Energy (ΔG) represent?

The energy available to do work.

When is a reaction non-spontaneous at all temperatures?

If ΔH is positive and ΔS is negative.

How does the Lewis theory define an acid?

As an electron pair acceptor.

Which of the following is a 'Monoprotic' acid?

HCl

Why don't H⁺ ions exist on their own in aqueous solution?

They immediately react with water to form H₃O⁺.

If a solution has a pH of 9.0, how is it classified?

Basic

According to the Arrhenius definition, what is a base?

A substance that ionizes to form OH⁻ in water.

How many times more acidic is a solution with a pH of 4.0 than a solution with a pH of 6.0?

100 times

What is a property of a basic solution?

Turns litmus paper blue.

What is the conjugate acid of the hydrogen phosphate ion, HPO₄²⁻?

H₂PO₄⁻

In the reaction HCO₃⁻ + H₂O ⇌ H₂CO₃ + OH⁻, what is the HCO₃⁻ ion acting as?

Brønsted-Lowry Base.

How are strong acids defined?

By the fact that they ionize 100% in water.

What should be changed to balance a chemical equation?

Balancing should be done by changing coefficients.

What products are formed from the complete combustion of a hydrocarbon in excess O2?

Complete combustion of a hydrocarbon in excess O2 produces CO2 and H2O.

What is the coefficient of O2 for the combustion of C3H8?

For the combustion of C3H8, the coefficient of O2 is 5.

What type of reaction is represented by C + AB -> CB + A?

C + AB -> CB + A represents a single-replacement reaction.

How are aqueous ionic compounds represented in the complete ionic equation?

Ionic compounds that are designated as aqueous are written as separate ions with charges in the complete ionic equation.

When does a precipitate form in a double-replacement reaction?

A precipitate forms in a double-replacement when one product is insoluble or slightly soluble.

What is NOT a usual driving force for double-replacement reactions?

Forming another soluble salt only is NOT a usual driving force for double-replacement reactions.

How is the reaction CaCO3(s) -> CaO(s) + CO2(g) classified?

The reaction CaCO3(s) -> CaO(s) + CO2(g) is best classified as a decomposition reaction.

Why will Zn displace Cu2+ in the reaction Zn(s) + CuSO4(aq)?

Zn will displace Cu2+ because Zn is above Cu in the activity series.

What is the net ionic equation for HCl(aq) + NaOH(aq) -> NaCl(aq) + H2O(l)?

The net ionic equation is H+ + OH- -> H2O.