7. what is the mass percent of a naoh solution prepared by dissolving 42 g of naoh in 145 g of water?\n8…
7. what is the mass percent of a naoh solution prepared by dissolving 42 g of naoh in 145 g of water?\n8. what is the mass percent of a nacl solution prepared by dissolving 57.4 g of nacl in 223.0 g of water?\n9. what is the mass/volume percent of a cu(no₃)₂ solution prepared by dissolving 55.3 g of cu(no₃)₂ to make 154 ml of solution?
Answer
7.
Explanation:
Step1: Calculate total mass of solution
Total mass = mass of solute + mass of solvent. Here, mass of NaOH (solute) is 42 g and mass of water (solvent) is 145 g. So, total mass $m_{total}=42 + 145=187$ g.
Step2: Calculate mass - percent
Mass - percent formula is $\text{Mass}%=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times100%$. Substitute values: $\text{Mass}%=\frac{42}{187}\times 100%\approx 22.5%$.
Answer:
$22.5%$
8.
Explanation:
Step1: Calculate total mass of solution
Total mass = mass of solute+mass of solvent. Mass of NaCl (solute) is 57.4 g and mass of water (solvent) is 223.0 g. So, $m_{total}=57.4 + 223.0 = 280.4$ g.
Step2: Calculate mass - percent
Using the formula $\text{Mass}%=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times100%$, substitute values: $\text{Mass}%=\frac{57.4}{280.4}\times 100%\approx 20.5%$.
Answer:
$20.5%$
9.
Explanation:
Step1: Recall mass/volume - percent formula
The mass/volume - percent formula is $\text{Mass/Volume}%=\frac{\text{Mass of solute (g)}}{\text{Volume of solution (mL)}}\times100%$.
Step2: Substitute values
Mass of $Cu(NO_3)_2$ (solute) is 55.3 g and volume of solution is 154 mL. So, $\text{Mass/Volume}%=\frac{55.3}{154}\times 100%\approx 35.9%$.
Answer:
$35.9%$