a stock solution is made by dissolving 66.05 g of (nh4)2so4 in enough water to make 250 ml of solution. a…

a stock solution is made by dissolving 66.05 g of (nh4)2so4 in enough water to make 250 ml of solution. a 10.0 ml sample of this solution is then diluted to 50.0 ml. given that the molar mass of (nh4)2so4 is 132.1 g/mol, what is the concentration of the new solution? use $m_iv_i = m_fv_f$ and molarity = $\frac{moles of solute}{liters of solution}$. 0.400 m 1.60 m 5.00 m 10.0 m
Answer
Explanation:
Step1: Calculate moles of solute in stock solution
$n=\frac{m}{M}=\frac{66.05\ g}{132.1\ g/mol}=0.5\ mol$
Step2: Calculate molarity of stock solution
$V_{stock}=250\ mL = 0.25\ L$ $M_{stock}=\frac{n}{V_{stock}}=\frac{0.5\ mol}{0.25\ L}=2\ M$
Step3: Use dilution formula
$M_iV_i = M_fV_f$, where $M_i = M_{stock}=2\ M$, $V_i = 10.0\ mL=0.01\ L$, $V_f = 50.0\ mL = 0.05\ L$ $M_f=\frac{M_iV_i}{V_f}=\frac{2\ M\times0.01\ L}{0.05\ L}=0.4\ M$
Answer:
0.400 M