Chemical Reactions

In a chemical equation, is it true that

• the reactant side and product side can have different numbers of atoms for each element
• there can be different elements on the reactant side and the product side
• the reactant and product side have the same atoms for each element

Tags

NGSS.MS-PS1-5

What is a coefficient?

• The small number on the right of the chemical symbol.
• The large number to the left of a formula.

Tags

NGSS.HS-PS1-7

Why must chemical equations be balanced?

• So that the equation doesn't explode
• The reaction won't happen until it is balanced
• Matter cannot be created or destroyed
• None of these

Tags

NGSS.HS-PS1-7

2Ca + O₂ --> 2CaO 
What is the 2 located behind oxygen (O) called?

• coefficient
• reactant
• subscript
• product

In the equation,
2Mg + O₂ --> 2MgO
which are the reactants?

• Mg and O2
• MgO
• Mg and MgO
• O2 and MgO

Tags

NGSS.MS-PS1-2

How many atoms of hydrogen (H), sulfur (S), and oxygen (O) are there in sulfuric acid (H₂SO₄)?

• H-6, S-4, O-4
• H-1, S-2, O-8
• H-2, S-1, O-4
• H-2, S-4, O-4

Tags

NGSS.MS-PS1-1

Which of the following IS a physical change?

• Getting a haircut
• Rusty metal
• sour milk
• A compound

Which of the following is a chemical change?

• water freezes to form ice
• sugar dissolves in water
• gasoline burns in a car engine
• a piece of metal expands when it is heated

Tags

NGSS.MS-PS1-2

Which of the following is an example of a chemical change?

• rusting of a bicycle
• painting a house
• washing a dog
• tearing up a newspaper

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

In any chemical reaction, the mass of the products is always:

• slightly less than the mass of the reactants
• much less than the mass of the reactants
• the same as the mass of the reactants
• greater than the mass of the reactants