Chemistry Practice

If a chemical reaction such as photosynthesis begins with 6 atoms of carbon (C), how many atoms of carbon (C) should be in the products?

• 12 atoms of carbon (C)

• 6 atoms of carbon (C)

• 3 atoms of carbon (C)

• 2 atoms of carbon (C)

How does a balanced chemical equation satisfy the Law of Conservation of Mass?

• During a chemical reaction, the total amount of matter stays the same.

• During a chemical reaction, matter is destroyed.

• During a chemical reaction, one or more new substances are formed.

• During a chemical reaction, the total number of atoms increases.

If 100 grams of vinegar and 5 grams of baking soda are poured in a container, a small amount of gas will be produced. What will the final mass of the products be if the gas is trapped in the container?

• 100 grams

• 104 grams

• 105 grams

• 110 grams

When 5 grams of silver nitrate are added to a 50 gram solution of potassium chloride, 2 grams of silver chloride form in the solution as a precipitate. After the reaction, the total mass of the solution is 55 grams. Which evidence from the experiment supports the law of conservation of mass?

• The final mass of the product equals the mass of the reactants.

• The final mass of the product is less than the mass of the reactants.

• The mass of the precipitate is less than the amount of silver nitrate.

• The mass of the precipitate is greater than the amount of silver nitrate.

Which of the following is a correctly written chemical equation that demonstrates the conservation of mass?

• 
• 
• 
• 

What is the total number of oxygen atoms on the reactant side of the equation shown below?

CH3COOH + NaHCO3 → CH3COONa + H2O + CO2

• 2

• 3

• 5

• 7

Which best explains how the chemical reaction shown below follows the law of conservation of mass?

2H2 + O2 → 2H2O

• The hydrogen and oxygen molecules combine to form water.

• Hydrogen and oxygen are held together by strong chemical bonds.

• There are hydrogen and oxygen atoms on both sides of the equation

• The same number of hydrogen and oxygen atoms are on both sides of the equation.

Which is true of any physical or chemical reaction?

• Mass increases.

• Mass decreases.

• Mass fluctuates.

• Mass is conserved.

In the equation below, suppose 11 grams of zinc react with 12 grams of hydrogen chloride to form 16 grams of zinc chloride and an unknown amount of hydrogen gas.

Zn + 2HCl → ZnCl2 + H2

Based on the Law of Conservation of Mass, how many grams of hydrogen gas will form?

• 1 gram

• 7 grams

• 19 grams

• 23 grams

Two substances react and the mass is recorded. The mass of the products does not equal the mass of the reactants. Which is the best explanation for the difference in the masses?

• The scale was not balanced.

• Some of the mixture spilled.

• Gas was produced and lost to the environment.

• Substances were added after the initial mass was recorded.