Nuclear fusion in the sun involves hydrogen (H) atoms combining to form helium (He). A student claims that since the atmosphere
2 answers:
You might be interested in
This an incomplete question, here is a complete question.
Calculate the empirical formula for each stimulant based on its elemental mass percent composition.
a. nicotine (found in tobacco leaves): C 74.03%, H 8.70%, N 17.27%
b. caffeine (found in coffee beans): C 49.48%, H 5.19 %, N 28.85% and O 16.48%
Answer:
(a) The empirical formula for the given compound is
(b) The empirical formula for the given compound is
Explanation:
<u>Part A: nicotine </u>
We are given:
Percentage of C = 74.03 %
Percentage of H = 8.70 %
Percentage of N = 17.27 %
Let the mass of compound be 100 g. So, percentages given are taken as mass.
Mass of C = 74.03 g
Mass of H = 8.70 g
Mass of N = 17.27 g
To formulate the empirical formula, we need to follow some steps:
Step 1: Converting the given masses into moles.
Moles of Carbon =
Moles of Hydrogen =
Moles of Nitrogen =
Step 2: Calculating the mole ratio of the given elements.
For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 1.23 moles.
For Carbon =
For Hydrogen =
For Nitrogen =
Step 3: Taking the mole ratio as their subscripts.
The ratio of C : H : N = 5 : 7 : 1
The empirical formula for the given compound is
<u>Part B: caffeine</u>
We are given:
Percentage of C = 49.48 %
Percentage of H = 5.19 %
Percentage of N = 28.85 %
Percentage of O = 16.48 %
Let the mass of compound be 100 g. So, percentages given are taken as mass.
Mass of C = 49.48 g
Mass of H = 5.19 g
Mass of N = 28.85 g
Mass of O = 16.48 g
To formulate the empirical formula, we need to follow some steps:
Step 1: Converting the given masses into moles.
Moles of Carbon =
Moles of Hydrogen =
Moles of Nitrogen =
Moles of Oxygen =
Step 2: Calculating the mole ratio of the given elements.
For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 1.03 moles.
For Carbon =
For Hydrogen =
For Nitrogen =
For Nitrogen =
Step 3: Taking the mole ratio as their subscripts.
The ratio of C : H : N : O = 4 : 5 : 2 : 1
The empirical formula for the given compound is
The way you calculate the empirical formula is to firstly assume 100g. To find each elements moles you take each elements percentage listed, times it by one mole and divide it by its atomic mass. (ex: moles of K =55.3g x 1 mole/39.1g, therefore there is 1.41432225 moles of Potassium) Once you’ve completed this for every element you list each elements symbol beside it’s number of moles and divide by the smallest number because it can only go into its self once. After you’ve done this, you’ve found your empirical formula, which is the simplest whole number ratio of atoms in a compound. I’ve added an example of a empirical question I completed last semester :)
