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Name Laboratory Instructor Lab Day &Time; Scott, 30 Date QUIZ 2 sample 30 pts In

ID: 953273 • Letter: N

Question

Name Laboratory Instructor Lab Day &Time; Scott, 30 Date QUIZ 2 sample 30 pts Instructions. This quiz is open lab notebook, closed everything else. You must show all work in order to get credit. Please report answers with proper units and significant figures 1. 2 pts) Was this experiment guantitative? 2. a· (2 pts) Brety, what is the purpose of the blank measurement (when the cuvette was filled with waterj? b. (3 pts) How many L of 0.750 M Cu) are needed to prepare 50.0 mL of 0.103 M solution? 3. An experiment was performed under identical conditions as yours. The absorbance of the penny solution was recorded as 0 231 absorbance units. A calabration plot of absorbance vs. concentration of Cull) (mM) yielded the following trendline equation: y 11591x 0.50 a. (3 pts) What is the concentration of the original penny solution? Page 1 of 2 b. 3 pts) How many grams of Cu are in this solution? c- (3 pts. If the percent Cu was determined to be 2.70%, what was the mass of the penny?

Explanation / Answer

1. Yes, the experiment is quantitative.

2. a) A blank measurement is used to standardize the instrument. It accounts for any errors in the measurement.

b) M1V1 = M2V2

(0.75 M)(V) = (50.0 mL)(0.103 M)

V = 6.86 mL