Here you will find information and material for experiment 4 quiz questions. These questions have been designed from previous quiz questions and review material. Because it would be impossible come up with or compile all past and future questions, the list below are areas you may want to focus on.

 

Memorize the Copper reactions

Though it may seem unfair, past quizzes have had questions asking for all the reactions performed for the lab and the type of reaction in some form or another. These reactions can be found in your lab manual (link). These reactions and their type are also listed below.

 
  • Reaction 1 (redox): Cu(s) + HNO3(aq) → Cu(NO3)2(aq) + H2O(l) + NO2(g)
    • HNO3 is a strong acid
    • NO2 is toxic
  • Reaction 2 (metathesis): Cu(NO3)2(aq) + Na2CO3(s) + H2O → CuCO3•Cu(OH)2(s) + NaNO3(aq) + CO2(g)
    • Reaction 2a (acid-base): HNO3(aq) + Na2CO3(s) → NaNO3(aq) + CO2(g) + H2O(l)
  • Reaction 3 (decomposition): CuCO3•Cu(OH)2(s) + heat → CuO(s) + H2O(l) + CO2(g)
  • Reaction 4 (metathesis): CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)
  • Reaction 5 (single displacement or redox): CuSO4(aq) + Mg(s) → MgSO4(aq) + Cu(s)
    • Reaction 5a (single displacement or redox): H2SO4(aq) + Mg(s) → MgSO4(aq) + H2(g)
      • H2 flammable gas, ensure bunsen burners are off
 

Concepts, terminology, procedure & safety

Understand concepts such as the Principle of Conservation of Mass and terminology like filtrate (see quiz below). It is also important to understand the purpose of key steps in the procedure and their purpose (see lab manual and overview page)


 

CALCULATING PERCENT YIELD

This lab will require you to calculate the percent yield of the copper. Percent yield is calculated by dividing your actual yield (mass of copper yield after the last reaction and drying) with the expected or theoretical yield (mass copper you initially used) multiplied by 100.

Percent Yield = (Actual Yield ÷ Theoretical Yield) x 100

 

A percent yield that is less than 100 means that you made less than what you were supposed to get. This could be a number of reasons such as loss of substance during transfer.

A percent yield that is more than 100 means that you have more than what you were supposed to get. This could be a number of reasons such as impurities or that the sample was not completely dry.

 
 

Questions 1-13 (click to enlarge)