Calculate the empirical formula for the following compound: potassium tartrate found in baking powder: 20.8% K, 2.7% H, 25.5% C, and 51.0% O

Take a 100 g sample. That will give you

20.8 g K
2.7 g H
25.5 g C
51.0 g O
Convert each to moles.
Then find the ratio of the elements to each other with the smallest number being 1.00. The easy way to do that is to divide the smallest number by itself and divide all of the other numbers by the same small number. Finally, round to whole numbers. However, check your numbers and what they are percentages of because SOMETHING is wrong here.

To calculate the empirical formula of a compound, we need to determine the simplest whole number ratio between the elements present in the compound.

Step 1: Convert the percentages to grams.
Given percentages:
Potassium (K): 20.8%
Hydrogen (H): 2.7%
Carbon (C): 25.5%
Oxygen (O): 51.0%

Assuming we have 100 grams of the compound, the masses of each element can be calculated as follows:

Potassium (K) = 20.8g (20.8% of 100g)
Hydrogen (H) = 2.7g (2.7% of 100g)
Carbon (C) = 25.5g (25.5% of 100g)
Oxygen (O) = 51.0g (51.0% of 100g)

Step 2: Convert the masses to moles.
To convert the masses to moles, we need to divide each mass by its respective molar mass. The molar masses of the elements are as follows:

Potassium (K): 39.10 g/mol
Hydrogen (H): 1.01 g/mol
Carbon (C): 12.01 g/mol
Oxygen (O): 16.00 g/mol

Using these values, we can calculate the moles of each element:

Moles of Potassium (K) = 20.8 g / 39.10 g/mol
Moles of Hydrogen (H) = 2.7 g / 1.01 g/mol
Moles of Carbon (C) = 25.5 g / 12.01 g/mol
Moles of Oxygen (O) = 51.0 g / 16.00 g/mol

Step 3: Determine the ratio.
Now, divide each of the moles by the smallest number of moles calculated in the previous step:

Divide Moles of Potassium (K) by the smallest number of moles
Divide Moles of Hydrogen (H) by the smallest number of moles
Divide Moles of Carbon (C) by the smallest number of moles
Divide Moles of Oxygen (O) by the smallest number of moles

Step 4: Simplify the ratio.
If necessary, simplify the ratio obtained in the previous step to obtain the simplest whole number ratio. The resulting ratio gives us the empirical formula of the compound.

For example, if the ratio is 2.5:1:3:2, we would multiply all the numbers by 2 to get a whole number ratio of 5:2:6:4.

Now, performing the calculations:

Moles of Potassium (K) = 20.8 g / 39.10 g/mol = 0.532 moles
Moles of Hydrogen (H) = 2.7 g / 1.01 g/mol = 2.673 moles
Moles of Carbon (C) = 25.5 g / 12.01 g/mol = 2.124 moles
Moles of Oxygen (O) = 51.0 g / 16.00 g/mol = 3.188 moles

The smallest number of moles is 2.124 moles, which corresponds to carbon (C). Dividing all the other moles by this value, we get the ratio:

Moles of Potassium (K): 0.532 moles / 2.124 moles = 0.25
Moles of Hydrogen (H): 2.673 moles / 2.124 moles = 1.26
Moles of Carbon (C): 2.124 moles / 2.124 moles = 1.00
Moles of Oxygen (O): 3.188 moles / 2.124 moles = 1.50

The ratio is approximately K:0.25, H:1.26, C:1.00, O:1.50.

To get the simplest whole number ratio, we can multiply the ratio by 4:

K: 0.25 x 4 = 1
H: 1.26 x 4 = 5
C: 1.00 x 4 = 4
O: 1.50 x 4 = 6

Therefore, the empirical formula for the compound is K4H5C4O6.