Question

an analytical chemist measures the amount of elements $e_1$ and $e_2$ in four samples of an unknown substance $x$:

sample	mass of $e_1$	mass of $e_2$
2	15.9 g	9.1 g
3	10.8 g	6.2 g
4	19.6 g	11.3 g

its known that $x$ contains no elements other than $e_1$ and $e_2$.
using this information, answer the questions in the table below.
is $x$ a pure substance or a mixture? if you dont have enough information to decide, choose cant decide.
if you said $x$ is a pure substance, calculate the mass of element $e_1$ the analytical chemist would find in a new 10.0 g sample of $x$. round your answer to 2 significant digits.

Explanation:

Step1: Calculate mass - ratio of $E_1$ to total mass for each sample

For sample 1: Total mass = $14.0 + 8.0=22.0$ g, mass - ratio of $E_1=\frac{14.0}{22.0}\approx0.636$
For sample 2: Total mass = $15.9 + 9.1 = 25.0$ g, mass - ratio of $E_1=\frac{15.9}{25.0}=0.636$
For sample 3: Total mass = $10.8+6.2 = 17.0$ g, mass - ratio of $E_1=\frac{10.8}{17.0}\approx0.635$
For sample 4: Total mass = $19.6 + 11.3=30.9$ g, mass - ratio of $E_1=\frac{19.6}{30.9}\approx0.634$
Since the mass - ratio of $E_1$ to the total mass is approximately the same in all samples, $X$ is a pure substance.

Step2: Calculate mass of $E_1$ in a 10.0 g sample

The mass - ratio of $E_1$ is approximately $0.636$.
Mass of $E_1$ in 10.0 g sample of $X$ = $0.636\times10.0 = 6.4$ g (rounded to 2 significant digits)

Answer:

Is $X$ a pure substance or a mixture? pure substance
If you said $X$ is a pure substance, calculate the mass of Element $E_1$ the analytical chemist would find in a new 10.0 g sample of $X$. 6.4 g