Balancing

What is the Law of Conservation of Mass?

• The amount of matter changes when reacted or changed.

• The mass of all reactants are changed during a physical or chemical change.

• The mass of the reactants equals the mass of the products.

• The mass of the products is different than the mass of the reactants.

Suppose a reaction were to happen in an open container lab. During the reaction, the scientists observes the chemical bubbles and produce a gas. During the analysis the scientists notices that the reactants weighed 20g when he started, and the product weighed 20g. Explain what happened.

• His chemical reaction defined the law of conservation of mass

• The products destroyed mass during the reaction

• The reactants created matter during the reaction.

• The amount of matter after the reaction changes

At the end of chemical reactions, what is the total mass of the reactants compared to the total mass of the products?

• The mass changes depending on the reaction

• The mass is the same

• The product is doubled

• The product is half the mass of the reactants.

When balancing equations, a _____ can be placed to the left of a formula of a substance to make the equations balanced.

• charge

• coefficient

• random number

• subscript

What coefficient should be used to make the following equation balanced? N2+O2-->__NO

• 1

• 2

• 3

• 4

In balancing a chemical equation, you need to count the number of _____ in each element on both sides of the equation.

In balancing a chemical equation, you need to placed a _________ before the element or compound.

What coefficient should be placed in hydrogen at the product to balance the equation?

• 4

• 3

• 2

• 1

What coefficient should you placed in carbon at the product side to balance the equation?

• 1

• 2

• 3

• 4

What coefficient should be placed in oxygen in the reactants to balance the equation?

• 2

• 3

• 4

• 5