SHOW CALCULATIONS & CORRECT NO. OF SIG FIGS 1) Match the chemical equation with
ID: 568842 • Letter: S
Question
SHOW CALCULATIONS & CORRECT NO. OF SIG FIGS 1) Match the chemical equation with reaction type. +2NaNO3(aq) Cu(NO3)2(aq) + 2NaOH(aq) ( Cu(OH)2(s) a) synthesis b) double displacement c) single displacement d) decomposition 2) During the first part of the experiment, concentrated nitric acid will be added to copper metal, producing a toxic reddish brown gas, NO2. You should a) perform this step in the fume hood and stay there until the brown gas is gone b) ask your lab partner to smell the gas just for fun 3) A 0.234 g sample of copper metal is recycled through the series of reactions. At the end, 0.123 g copper is recovered. What is the copper metal percent recovery? Fill in ALL blanks. g X 100 =Explanation / Answer
1.
(b) Double displacement reaction becuase the cations exchange their anions.
2.
Cu (s) + 4 HNO3 (aq.) ----------> Cu(NO3)2 (aq.) + 2 H2O(l) + 2 NO2 (g)
3.
% Yield = Actual mass * 100 / Initial mass = 0.123 * 100 / 0.234 = 52.6 %
4.
Volume of HNO3 = 1.50 * 1 / 20 = 0.075 mL
Moles of HNO3 = molarity * volume / 1000 = 16 * 0.075 / 1000 = 0.0012 mol
From the balanced equation,
4 mol of HNO3 needs 1 mol of Cu
then,
0.00120 mol of HNO3 needs 0.00120 * 1 / 4 = 0.000300 mol of Cu
Mass of Cu required = 0.000300 * 63.54 = 0.0191 g.
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