1) Cu+2 forms which color when dissolved in water? A) clear B) orange C) blue D)
ID: 1004270 • Letter: 1
Question
1) Cu+2 forms which color when dissolved in water?
A) clear
B) orange
C) blue
D) black
2) Calculate the percent recovery of copper if: 1.5-g is the initial amount and 1.2-g is the amount recovered.
3)Which of the following is NOT a good explanation/indication as to the results obtained in the above question? ( hint name of the experiment copper Cycle).
A) at the end of reaction 2, the solution was a blue-gran color.
B) In reaction 2, the litmus paper revealed the solution was acidic.
C) At the end of step 5 the copper not fully dried
D) In reaction 4, black particles were noted in the filtrate.
4 )Calculate the percent recovery of copper if: 6.2-g is the initial amount and 8.7-g is the amount recovered.
5) Which of the following is NOT a good explination/indication as to the results obtained in the above question?
A) At the beginning of step 3, the student did not heat the mixture long enough.
B) The student misread the scale and recorded a larger number than the actual mass of the recovered copper.
C) The student recorded a smaller number than the actual mass of the initial copper.
D) At the end of step 5 the copper was not fully dried.
A) At the beginning of step 3, the student did not heat the mixture long enough.
B) The student misread the scale and recorded a larger number than the actual mass of the recovered copper.
C) The student recorded a smaller number than the actual mass of the initial copper.
D) At the end of step 5 the copper was not fully dried.
Explanation / Answer
1) Option C Blue
Cu+2 when dissolved in water forms [Cu(H2O)6]2+ which is blue in color.
2) Calculate the percent recovery of copper if:
Initial weight of Cu = 1.5g
Recovered weight of Cu =1.2g
% percent recovery of copper =( recovered weight of Cu/ initial weight of Cu) x 100
=( 1.2/ 1.5) x 100
= 80%
3)
D) In reaction 4, black particles were noted in the filtrate. is NOT a good explanation
CuO +2 HCl ----à CuCl2 + H2O
CuCl2 is formed in reaction 4, which is green in color.
4) Calculate the percent recovery of copper if
Initial weight of Cu = 6.2g
Recovered weight of Cu =8.7g
% percent recovery of copper =( recovered weight of Cu/ initial weight of Cu) x 100
=( 8.7/6.2) x 100
= 140%
5)
A) At the beginning of step 3, the student did not heat the mixture long enough is NOT a good explanation. Other options B, C and D give correct explanations for why the recovered weight of Cu is more than the initial weight of Cu.
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