Stoichiometry Conversions

4 Al + 3 O₂ –> 2 Al₂O₃  How much aluminum would be needed to completely react with 45 grams of O₂?

• 1.05 moles
• 3.75 moles
• 1.875 grams
• 1.875 moles

From the reaction: B₂H₆ + 3O₂ -->2 HBO₂ + 2 H₂O
 What mass of O₂ will be needed to burn 36.1 g of B₂H₆?

• 13.8 g O₂
• 3.86 mol of O₂
• 124 g O₂

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NGSS.HS-PS1-7

N₂ +  3H₂ −->  2NH₃ 
How many moles of hydrogen are needed to react with 2 moles of nitrogen?

• 6
• 2
• 3
• 1

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NGSS.HS-PS1-7

For the reaction represented by the equation Cl₂ + 2KBr → Br₂ + 2KCl, how many grams of potassium chloride (KCl) can be produced from 356 grams potassium bromide (KBr)? Round to one decimal point when calculating.

• 749 g

• 223 g

• 479 g

• 814 g

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NGSS.HS-PS1-7

Use the following equation:

2Al + 3Cl2 → 2AlCl3

If 140 grams of aluminum chloride react, how many moles of aluminum will be produced?

• 5.10 moles of Al

• 1.05 moles of Al

• 2.25 moles of Al

• 3.42 moles of Al

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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

Use the equation 2 Al + 3 Cl₂ ---> 2 AlCl₃.  If 2 moles of aluminum and 2 moles of chlorine are reacted, identify the limiting reactant.

• AlCl3
• Cl2
• Al

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NGSS.HS-PS1-7

4NH₃ + 5O₂ --> 4NO + 6H₂O
How many grams of NO are formed if 6.30g of ammonia react with 1.80g of oxygen? 

• 0.37g
• 0.045g
• 1.35g
• 11.1g

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NGSS.HS-PS1-7

What is a limiting reactant?

• the reactant that determines how much product can be made
• the reactant that is in excess
• the product that you can make the most of
• the amount of reactants that react with each other

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NGSS.HS-PS1-7

How many grams are in 7.8 moles of NaCl?

• 476grams
• 460 grams
• 452 grams
• 462 grams

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NGSS.HS-PS1-7