Question

Suppose there are two known compounds containing the generic elements X and Y. You have a 1.00-g sample of each compound. One sample contains 0.25 g of X and the other contains 0.33 g of X. Identify plausible sets of formulas for these two compounds. Check all that apply.

Answer 1

To identify plausible sets of formulas for two compounds containing elements X and Y, use the given masses to calculate the ratios and apply the law of multiple proportions to determine simple whole-number ratios for potential empirical formulas.

Step-by-step explanation:

The question is regarding the identification of plausible sets of formulas for two compounds containing generic elements X and Y based on the amounts of element X in both compounds. By using the mass data provided (0.25 g and 0.33 g of X), along with the total sample mass (1.00 g for each compound), we can find the respective amounts of element Y in each compound (0.75 g and 0.67 g of Y, respectively).

Then, by taking the ratios of the masses of X to Y for each compound, we can determine simple whole-number ratios, which can suggest possible empirical formulas for the compounds. These formulas are based on the law of multiple proportions, which states that if two elements form more than one compound between them, then the ratios of the masses of the second element that combine with a fixed mass of the first element will be ratios of small whole numbers.

Answer 2

I think the correct answers are X2Y and X3Y, X2Y5 and X3Y5, and X4Y2 and X3Y, for the following reason:

If you look at the combining masses of X and Y in each of the two compounds,

The first compound contains 0.25g of X combined with 0.75g of Y
so the ratio (by mass) of X to Y = 1 : 3

The second compound contains 0.33 g of X combined with 0.67 g of Y
so the ratio (by mass) of X to Y = 1 : 2

Now, you suppose to prepare each of these two compounds, starting with the same fixed mass of element Y ( I will choose 12g of Y for an easy calculation!)

The first compound will then contain 4g of X and 12g of Y
The second compound will then contain 6g of X and 12g of Y

The ratio which combined the masses of X and the fixed mass (12g) of Y
= 4 : 6
or 2 : 3

So, the ratio of MOLES of X which combined with the fixed amount of Y in the two compounds is also = 2 : 3

The two compounds given with the plausible formula must therefore contain the same ratio.