Study Guide - Chemical Reactions & Law of Conservation of Mass

What are the reactants in this equation?

• N₂ and H₂

• NH₃ and H₂

• N₂ and NH₃

• NH₃ and O₂

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

What are the products?

• NH₃

• CO₂

• H₂O

• O₂

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

NGSS.MS-PS1-1

What do we call the little 2 in N₂? What does it tell us?

• The little 2 is called a subscript. It tells us there are 2 atoms of nitrogen in a molecule of N₂.

• The little 2 is called a superscript. It tells us there are 2 molecules of nitrogen.

• The little 2 is called a coefficient. It tells us there are 2 electrons in nitrogen.

• The little 2 is called an exponent. It tells us there are 2 protons in nitrogen.

Tags

NGSS.MS-PS1-1

What do we call the 3 in 3H₂? What does it tell us?

• The 3 is called a coefficient. It tells us there are 3 molecules of H₂.

• The 3 is called a subscript. It tells us there are 3 atoms of hydrogen in each molecule.

• The 3 is called an exponent. It tells us the energy level of hydrogen.

• The 3 is called a prefix. It tells us the charge of the molecule.

Tags

NGSS.MS-PS1-1

The statement “mass is conserved during a chemical reaction” means:

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

• Mass increases during a chemical reaction.

• Mass disappears during a chemical reaction.

• The mass of the products is always greater than the reactants.

Tags

NGSS.MS-PS1-5

A piece of ice with a mass of 15 g is put in a beaker and melted. The mass of the melted ice should be…

• 15 g

• Higher than 15 g

• Lower than 15 g

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

This equation is balanced or unbalanced. Select the correct answer and explain how you know.

• The equation is balanced because the number of atoms of each element is the same on both sides.

• The equation is unbalanced because the number of atoms of each element is not the same on both sides.

• The equation is balanced because the reactants and products are the same compounds.

• The equation is unbalanced because the products are different from the reactants.

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

In a chemical reaction, only the atoms in the ____________________ can end up in the products.

• reactants

• products

• catalysts

• solvents

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

If two substances react and the temperature increases, the reaction is ________________.

• exothermic

• endothermic

• neutral

• catalytic

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

If two substances react and the temperature decreases, the reaction is ________________.

• endothermic

• exothermic

• combustion

• neutralization

Tags

NGSS.HS-PS1-4