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General Chemistry

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The following reactions were conducted in a lab for studies related to reaction kinetics. Consider the reactions shown below:


Which of the following is the actual formula of dextrose, if the empirical proportion is 1:2:1, where the proportion number 2 is that of hydrogen. Dextrose has a molecular weight of 180 g/mol? (Dextrose molecule is composed of carbon, hydrogen, and oxygen)

A CHO
B C6H12O6
C C12H6O3
D CH2O
Ans. B From the question, we can say that the empirical formula of dextrose is CH2O. The molecular weight of dextrose is also given. Let's first calculate the weight of the empirical formula. Maybe the empirical formula represents the actual formula. The weight of the empirical formula is 30 g/mol. But the question says it is 180 g/mol. In this case, the molecular formula is not the same as the empirical formula. By dividing the actual weight by the empirical weight, we will get the coefficient with which we have to multiply the empirical formula to get the actual formula. The coefficient is 180/30 = 6. So the molecular formula is C6H12O6. Have you heard of glucose? Well, dextrose is the same thing. If you knew that, you could have picked the answer right away. But more importantly, it is the process that you have to learn from this question.

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