CHEM (Sem II) Unit 1: Stoich Exam Review

What is the conversion factor that is found in all stoichiometry problems?

• Density Ratio
• Avagadro's Number
• Mole Ratio

How does a scientist determine ACTUAL yield?

• They pick a randon number.
• They must collect it during an actual lab or experiment.
• They calculate it using exact numbers and find the ideal quantities.
• Pluto

True or False: % yield ultimately represents the efficiency of the chemical reaction set up by the scientist.

• True
• False

Tags

NGSS.HS-PS1-6

Given the equation: 2Al + 3MgCl2 --> 2AlCl3 + 3Mg, how many moles of aluminum are produced from 5 moles of magnesium chloride?

• 3.3 moles
• 10 moles
• 5 moles

Tags

NGSS.HS-PS1-7

In the equation 2H20 --> H2 + O2, what is the molar ratio of water to oxygen gas?

• 1 to 1
• 2 to 1
• 1 to 2

Tags

NGSS.HS-PS1-7

Which of the following best describes stoichiometry?

• The study of the quantity of relationships between the reactants and products in a chemical reaction.
• The study of the how much matter takes up space in a vacuum.
• The study of periodic trends and how they relate to intermolecular forces.

What is the % yield if the actual yield is 5.5 grams and the theoretical yield is 7 grams?

• 1.27
• 0.79
• 0.35

Tags

NGSS.HS-PS1-7

According to this equation: 2HgO --> 2Hg + O2. Given that the density of oxygen is 1.439 g/L, how many liters of oxygen gas can be produced if 2 moles of mercury (II) oxide are heated?

• 44 L

• 11 L

• 22 L

• 33 L

In the chemical reaction N2 + H2 --> NH3, how many molecules of NH3 are produced if 4 moles of nitrogen gas is used?

• 4.82 x 10 ^24 NH3 molecules
• 2.41 x 10^24 NH3 molecules
• 3.45 x 10^24 NH3 molecules

Tags

NGSS.HS-PS1-7

All stoichiometry problems involve starting with information about one substance and finding information about a different substance. What is always involved in "making the switch?"

• only balanced equations
• only mole ratios
• mole ratio from balanced equation