Defining Stoichiometry

What is the scientific law that states that matter is not created or destroyed but only transformed in a chemical reaction?

• law of conservation of energy

• law of conservation of mass

• law of conservation of momentum

• law of gravity

What do the coefficients in the following balanced chemical equation mean?

2H₂ + O₂ → 2H₂O

• 2 moles of hydrogen and 1 mole of oxygen in the reactants

• 2 moles of oxygen and 1 mole of hydrogen in the reactants

• 2 moles of oxygen and 1 mole of hydrogen in the products

• 2 moles of hydrogen and 1 mole of oxygen in the products

What is the first thing you must do to solve a stoichiometry problem?

• Write a Balanced Equation
• Panic
• Write an Unbalanced Equation
• Ask for help

Tags

NGSS.HS-PS1-7

KNO₃ --> KNO₂ + O₂
What coefficients are needed to balance the reaction?

• 2, 2, 1
• 2, 3, 2
• 1, 2, 2
• 1, 3, 1

Tags

NGSS.HS-PS1-7

Mole ratios are obtained from the

• balanced chemical equation
• periodic table
• molar mass

Tags

NGSS.HS-PS1-7

When does a chemical reaction stop?

• When the lab is finished
• When the excess reactant is used up
• When the limiting reactant is used up
• Chemical reactions never stop

In the equation 2 Al2O3 --> 4 Al + 3 O2, what is the mole ratio of aluminum to oxygen?

• 10:6 
• 3:4
• 4:3
• 2:3

Tags

NGSS.HS-PS1-7

What can be determined from a balanced chemical equation?

• Mole ratio of any two substances in the reaction
• Energy released in the reaction.
• Electron configuration of all elements in the reaction. 
• Mechanism involved in the reaction. 

Tags

NGSS.HS-PS1-4

NGSS.HS-PS1-7

Given the reaction: 4Al + 3O₂ --> 2Al₂O₃
How many moles of Aluminum oxide do you have if you have 2 moles of Al?

• 3 mole
• 2 mole
• 1 mole
• 0.5 mole

Tags

NGSS.HS-PS1-7

BALANCED chemical equations tell you the relative amounts or the ratios of reactants and products. 

Use the following BALANCED chemical equation to determine the ratio:
 $4NH_3+6NO\ \rightarrow\ 5N_2+6H_2O$   
What is the ratio of  $NH_3$   to  $N_2$  

• 4:5

• 1:1

• 2:3

• 5:6

Tags

NGSS.HS-PS1-7