Question

a certain sugar used in treating patients with low blood sugar has the following chemical composition: 40 percent carbon, 6.7 percent hydrogen, and 53.3 percent oxygen. what is the empirical formula? the molar mass of the compound is 180 grams/mole. what is the molecular formula of this compound?

Explanation:

Step1: Assume 100g of sugar

Mass of C = 40g, mass of H = 6.7g, mass of O = 53.3g

Step2: Calculate moles of each element

$n_C=\frac{40g}{12g/mol}\approx3.33mol$, $n_H=\frac{6.7g}{1g/mol}=6.7mol$, $n_O=\frac{53.3g}{16g/mol}\approx3.33mol$

Step3: Find mole - ratio

$C:H:O = 3.33:6.7:3.33\approx1:2:1$, empirical formula is $CH_2O$

Step4: Calculate empirical - formula mass

$M_{empirical}=12 + 2\times1+16 = 30g/mol$

Step5: Find multiple n

$n=\frac{180g/mol}{30g/mol}=6$

Step6: Determine molecular formula

Molecular formula is $C_6H_{12}O_6$

Answer:

$C_6H_{12}O_6$