Answer to Question #130935 in Molecular Physics | Thermodynamics for Johannes Steven

Question

1. 500 mL C2H6 was measured at STP, Determine how many grams of C2H6 were measured.

2. The mass percentage composition of sodium metal in 58.44 g NaCl is about 39.34%, Determine the percentage composition of sodium in 1000 g of NaCl.

Answer 1

Question 1

$\nu=\frac{m}{M}=\frac{V}{V_m}$ whence $m=\frac{VM}{V_m}$

$M(C_2H_6)=110\frac{gram}{mole}$

Molar volume $V_m=22.4$ (L)

$m=\frac{500*10^{-3}*110}{22.4}=2.5$ (g)

Question 2:

If W is the mass percentage, it has the linear dependence from mass.

$W_1-m_1 W_2-m_2$

$\frac{W_1}{W_2}=\frac{m_1}{m_2}$

$W_2=\frac{m_2}{m_1}W_1$

$W_2=\frac{1000}{58.44}*0.3934=0.023=6.73$ (it's a very big number)