Understanding Chemical Reactions and Equations

What are the reactants in the combustion of methane?

• Oxygen and carbon dioxide

• Methane and oxygen

• Carbon and hydrogen

• Carbon dioxide and water

Why do we use O2 instead of O for oxygen in chemical equations?

• Because oxygen is always found as a single atom

• Because oxygen is a solid

• Because oxygen naturally exists as two atoms bonded together

• Because it makes the equation easier to balance

What is the first rule of balancing chemical equations?

• You can change the small numbers

• You can use fractions

• You must use whole numbers

• You cannot change the small numbers

Tags

NGSS.HS-PS1-7

Why is it important to balance chemical equations?

• To use up all reactants

• To make the equation look neat

• To follow the law of conservation of mass

• To ensure the reaction can occur

Tags

NGSS.HS-PS1-7

How do we adjust the number of oxygen atoms in the methane combustion equation?

• By removing CO2 from the equation

• By changing the chemical formula of oxygen

• By adding a coefficient in front of O2

• By adding a coefficient in front of CH4

Tags

NGSS.HS-PS1-7

What does adding a coefficient in front of a chemical formula indicate?

• Change in the chemical structure

• The number of atoms in a molecule

• Change in the physical state

• The number of molecules of that substance

What element do we balance first in the sulfuric acid and sodium hydroxide reaction?

• Oxygen

• Hydrogen

• Sodium

• Sulfur

How do we correct the imbalance of sodium in the sulfuric acid reaction?

• By adding more water to the products

• By removing water from the products

• By adding a coefficient in front of sodium hydroxide

• By adding more sulfuric acid

Tags

NGSS.HS-PS1-7

NGSS.HS-PS1-6

What indicates that a chemical equation is balanced?

• When there is an equal number of each type of atom on both sides

• When there are no coefficients needed

• When the equation looks symmetrical

• When all elements are present on both sides

Tags

NGSS.MS-PS1-5