Density And Law Of Conservation Of Mass

1. What are the units for density?

G/m

M/mL

G/cm3

Cm3/mL

The correct answer is g/cm3 because density is defined as mass per unit volume. The unit for mass is grams (g) and the unit for volume is cubic centimeters (cm3). Therefore, the units for density are grams per cubic centimeter (g/cm3).

Explanation

The correct answer is g/cm3 because density is defined as mass per unit volume. The unit for mass is grams (g) and the unit for volume is cubic centimeters (cm3). Therefore, the units for density are grams per cubic centimeter (g/cm3).

2. What pieces of equipment are used to calculate the density of a liquid?

Graduated cylinder, meter stick

Beaker, stop watch

Graduated cylinder, triple beam balance

Beaker, triple beam balance

A graduated cylinder is used to measure the volume of the liquid, while a triple beam balance is used to measure the mass of the liquid. To calculate the density of a liquid, the mass and volume need to be determined, and dividing the mass by the volume gives the density. Therefore, a graduated cylinder and a triple beam balance are the correct pieces of equipment to use for calculating the density of a liquid.

Explanation

A graduated cylinder is used to measure the volume of the liquid, while a triple beam balance is used to measure the mass of the liquid. To calculate the density of a liquid, the mass and volume need to be determined, and dividing the mass by the volume gives the density. Therefore, a graduated cylinder and a triple beam balance are the correct pieces of equipment to use for calculating the density of a liquid.

3. If all the reactants in a chemical reaction are completely used, which of the following statements accurately describes the relationship between the reactants and the products?

The products must have different physical state than the reactants.

The total mass of the reactants must equal the total mass of the products.

The reactants must contain more complex molecules than the products do.

The density of the reactants must equal the density of the products.

Law of conservation of Mass:
Mass of Reactants = Mass of Products

Explanation

Law of conservation of Mass:
Mass of Reactants = Mass of Products

4. As the viscosity of a liquid increases, the liquid —

Conducts electricity

Pours more slowly

Evaporates more quickly

Forms a precipitate

As the viscosity of a liquid increases, the liquid pours more slowly. Viscosity is a measure of a liquid's resistance to flow. When a liquid has high viscosity, its molecules are more tightly packed together, resulting in more friction between them. This increased friction makes it more difficult for the liquid to flow, causing it to pour more slowly.

Explanation

As the viscosity of a liquid increases, the liquid pours more slowly. Viscosity is a measure of a liquid's resistance to flow. When a liquid has high viscosity, its molecules are more tightly packed together, resulting in more friction between them. This increased friction makes it more difficult for the liquid to flow, causing it to pour more slowly.

5. When a 1-kilogram log was burned, 0.05 kilogram of ash was produced. The mass of the ash is less than the mass of the log because —

Wind carried away some matter before it burned

Some matter was converted to gases that were released

Combustion changed some matter into energy

Some matter was decomposed by organisms in the soil

When a log is burned, the process of combustion converts some of the matter in the log into gases. These gases are then released into the atmosphere. As a result, the mass of the log decreases, and some of the matter is no longer present in the form of ash. Therefore, the mass of the ash produced is less than the mass of the log.

Explanation

When a log is burned, the process of combustion converts some of the matter in the log into gases. These gases are then released into the atmosphere. As a result, the mass of the log decreases, and some of the matter is no longer present in the form of ash. Therefore, the mass of the ash produced is less than the mass of the log.

6. Use the following reaction to answer the question: K + H₂O → KOH + H₂What is the coefficient for H₂O when the above equation is balanced?

1

2

3

4

The number of atoms in the reactants side MUST be the same number of atoms as in the products.

Explanation

The number of atoms in the reactants side MUST be the same number of atoms as in the products.

7. Which process best demonstrates a chemical change in distilled water?

Freezing water.

Separating water into its elements.

Calculating density.

Dissolving sugar in water.

Chemical changes change the reactant into new products.

Explanation

Chemical changes change the reactant into new products.

8. What is the density at 20˚C of 12.0 milliliters of a liquid that has a mass of 4.05 grams?

0.33 g/mL

2.96 g/mL

16.1 g/mL

48.6 g/mL

The density of a substance is calculated by dividing its mass by its volume. In this case, the mass of the liquid is given as 4.05 grams and the volume is given as 12.0 milliliters. Dividing the mass by the volume gives a density of 0.33 g/mL.

Explanation

The density of a substance is calculated by dividing its mass by its volume. In this case, the mass of the liquid is given as 4.05 grams and the volume is given as 12.0 milliliters. Dividing the mass by the volume gives a density of 0.33 g/mL.

9. When CaCO₃ is heated, it forms CaO and CO₂. Which of these statements best describes the mass of the products if 100 g of CaCO₃ is heated?

The difference in the products’ masses is equal to the mass of the CaCO3.

The sum of the products’ masses is less than the mass of the CaCO3.

The mass of each product is equal to the mass of the CaCO3.

The sum of the products’ masses equals the mass of the CaCO3.

Mass of Reactants = Mass of Products
Law of Conservation of Mass: Mass cannot be created nor destroyed, only transformed.

Explanation

Mass of Reactants = Mass of Products
Law of Conservation of Mass: Mass cannot be created nor destroyed, only transformed.