Stoichiometry

The number of significant figures in an answer to a stoichiometry problem is determined only by

• the number of significant figures of any measured quantities in the problem.
• the number of decimal places in the molar masses of substances in the chemical equation.
• the number of significant figures in the mole ratio used to solve the problem.
• The number of significant figures in the molar masses of substances in the chemical equation.

What is the molar mass of Mg(NO₃)₂

• 148.313g/mol
• 134.306g/mol
• 54.311g/mol

What is the molar mass of C₆H₁₂O₆?

• 180
• 72
• 29
• 174

Using the following equation:
Fe₂O₃(s) + 3H₂(g) → 2Fe(s) + 3H₂O(l)
How many moles of iron can be made from  6 moles H₂? 

• 4 moles Fe
• 6 moles Fe
• 9 moles Fe
• 2 moles Fe

Tags

NGSS.HS-PS1-7

For the Balanced Reaction: 3 Mg + 1 Fe₂O₃ → 3 MgO + 2 Fe; What is the Ratio of moles of MgO to moles Fe?

• 3mol Mg / 2 mol Fe
• 2 mol Mg/ 3 mol Fe
• 1 mol Fe/ 2 mol Fe
• 3 mol MgO / 2 mol Fe

Tags

NGSS.HS-PS1-7

Which of the following is NOT a reason why actual yield is less than theoretical yield?

• loss of product during purification
•  conservation of mass
• competing side reactions
• impure reactants present

How many significant figures does the following number have: 231

• 2
• 3
• Whole number is not possible
• None of the above

The type of stoichiometry problem that involves the most steps is a 

• mass-to-mole conversion
• mole-to-mass conversion
• mass-to-mass conversion
• mole-to-mole conversion

In every chemical reaction, _____.

• mass and molecules are conserved.
• moles and liters are conserved.
• mass and atoms are conserved.
• moles and molecules are conserved. 

Tags

NGSS.HS-PS1-7

When an equation is used to calculate the amount of product that will form during a reaction, then the value obtained is called the ____________.

• minimum yield
• actual yield
• percent yield
• theoretical yield