Question

12 calculate the mass of ammonium sulfate to prepare a 1.5m solution in 40 ml of di water. the molar mass of ammonium sulfate is 132.14 g/mol. 13 calculate the potassium chloride, kcl, to prepare a 1m solution in 100 ml of di water. molar mass = 74.55 g/mol

Explanation:

Step1: Convert volume to liters

We know that $1L = 1000mL$. So for the first - case, $V_1=40mL = 40\times10^{- 3}L=0.04L$, and for the second - case, $V_2 = 100mL=100\times10^{-3}L = 0.1L$.

Step2: Use the molarity formula $n = M\times V$ to find the number of moles

For ammonium sulfate ($(NH_4)_2SO_4$), with $M_1 = 1.5M$ and $V_1=0.04L$, the number of moles $n_1$ is $n_1 = M_1\times V_1=1.5mol/L\times0.04L = 0.06mol$.
For potassium chloride ($KCl$), with $M_2 = 1M$ and $V_2 = 0.1L$, the number of moles $n_2$ is $n_2 = M_2\times V_2=1mol/L\times0.1L = 0.1mol$.

Step3: Use the formula $m=n\times M$ to find the mass

For ammonium sulfate, with $n_1 = 0.06mol$ and molar mass $M_{(NH_4)_2SO_4}=132.14g/mol$, the mass $m_1$ is $m_1=n_1\times M_{(NH_4)_2SO_4}=0.06mol\times132.14g/mol = 7.9284g\approx7.93g$.
For potassium chloride, with $n_2 = 0.1mol$ and molar mass $M_{KCl}=74.55g/mol$, the mass $m_2$ is $m_2=n_2\times M_{KCl}=0.1mol\times74.55g/mol = 7.455g\approx7.46g$.

Answer:

The mass of ammonium sulfate is approximately $7.93g$ and the mass of potassium chloride is approximately $7.46g$.