We can calculate the mass percent of an element by dividing its atomic mass by the mass of the compound and then multiply by 100:
% by mass of element = (mass of element/mass of compound) x100%
Impurities like n-eicosane with the molecular formula C20H42 could account for the low percent by mass of oxygen in the sample because it has a zero percent oxygen based on its compound formula which indicates that it does not have the element oxygen.

7 0

2 years ago

A 2400.-gram sample of an aqueous solution contains 0.012 gram of nh3. What is the concentration of nh3 in the solution

Kryger [21]

Answer : The concentration of $NH_3$ in the solution is, $2.94\times 10^{-4}M$

Explanation :

First we have to calculate the volume of aqueous solution that is water.

Density of water = 1.00 g/mL

Mass of water = 2400 g

$\text{Volume of water}=\frac{Mass}{Density}=\frac{2400g}{1.00g/mL}=2400mL$

Now we have to calculate the concentration of ammonia solution.

Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.

Formula used :

$\text{Molarity}=\frac{\text{Mass of }NH_3\times 1000}{\text{Molar mass of }NH_3\times \text{Volume of solution (in mL)}}$

Molar mass of $NH_3$ = 17 g/mole

Now put all the given values in this formula, we get:

$\text{Molarity}=\frac{0.012g\times 1000}{17g/mole\times 2400mL}=3.12mole/L=2.94\times 10^{-4}M$

Therefore, the concentration of $NH_3$ in the solution is, $2.94\times 10^{-4}M$

7 0

1 year ago