Question

bronze analysis
dissolving the bronze
he then dissolves a 5.05 gram bearing in nitric acid. the sample turns a light blue color as the metal dissolves.

assume the entire bearing is made of copper. how much 8.0 m hno₃ would be needed to dissolve the entire bearing according to the reaction below?
$4\text{hno}_3 + \text{cu} \
ightarrow \text{cu(no}_3\text{)}_2 + 2\text{no}_2 + 2\text{h}_2\text{o}$

what volume of 8.0 m hno₃ would be needed to dissolve the entire bearing, assuming it was entirely copper?
2.5 ml

1. ml

640 ml
2.5 ml

Explanation:

Step1: Calculate moles of Cu

Molar mass of Cu = 63.55 g/mol.
Moles of Cu = $\frac{\text{Mass of Cu}}{\text{Molar mass of Cu}} = \frac{5.05\ \text{g}}{63.55\ \text{g/mol}} \approx 0.0795\ \text{mol}$

Step2: Relate moles of Cu to HNO₃

From reaction: 1 mol Cu reacts with 4 mol HNO₃.
Moles of HNO₃ = $4 \times \text{Moles of Cu} = 4 \times 0.0795\ \text{mol} = 0.318\ \text{mol}$

Step3: Calculate volume of HNO₃

Molarity $M = \frac{\text{Moles}}{\text{Volume (L)}}$, so Volume = $\frac{\text{Moles}}{M}$
Volume of HNO₃ = $\frac{0.318\ \text{mol}}{8.0\ \text{mol/L}} = 0.03975\ \text{L} \approx 40.0\ \text{mL}$

Answer:

B. 40. mL