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ANSWER
[tex]\begin{gathered} \text{The empirical formula of the sample is} \\ \text{CaBr}_2\text{ --------------> Calcium bromide} \end{gathered}[/tex]STEP-BY-STEP EXPLANATION:
Given parameters
• The grams of the total sample = 40 grams
,• The gram of calcium in the sample = 8 grams
Recall that, the sample contains calcium and bromine
Hence, we need to calculate the mass of bromine in the sample.
Sample = Calcium + bromine
40 = 8 + bromine
Substract 8 from both sides
40 - 8 = 8 - 8 + bromine
Bromine = 32 grams
Hence, the mass of bromine in the sample is 32 grams
The next thing is to find the number of moles of each element
[tex]\text{Mole = }\frac{\text{ reacting mass}}{\text{molar mass}}[/tex]Let the molar mass of each element be;
• Calcium = 40 g/mol
,• Bromine = 79.904 g/mol
[tex]\begin{gathered} \text{mole of calcium = }\frac{8}{40} \\ \text{mole of calcium =0.2 mole} \end{gathered}[/tex][tex]\begin{gathered} \text{Mole of Bromine = }\frac{32}{79.904} \\ \text{mole of bromine = 0.400 mole} \end{gathered}[/tex]From the mole calculated, the lowest number of moles is 0.2 which is the calcium element.
The next thing is to divide through by 0.2 mole which is the lowest mole
Ca Br
0.2 0.40
0.2 0.2
1 2
Hence, the empirical formula is given below as
[tex]\begin{gathered} \text{The empirical formula of the sample is } \\ \text{CaBr}_2\text{ -----------> Calcium bromide} \end{gathered}[/tex]