A compound contains 38.7% K, 13.9% N, and 47.4% O by mass. What is the empirical formula of the compound?
38.7% K =38.7g of K, 13.9% N= 13.9g of N, and 47.4% O =47.4g of O
38.7g of K*(1 mole of K/39.1g of K)=0.990 moles of K
13.9g of N*(1 mole of N/14.0g of N)=0.993 moles of N
47.4g of O*(1 mole of O/16.0g of O)=2.96 moles of O
Take the lowest number of moles and divide into each number of moles.
K=0.990/0.990=1
N=0.993/0.990=1
O=2.96/0.990=3
Empirical formula is KNO3
I left a note for you concerning your 1J calculation for physics.
Well, let's see if we can solve this using some elemental humor!
Okay, so we have K, N, and O in our compound.
38.7% K? That's quite a "potassium" you've got there!
13.9% N? Nitrogen, huh? Well, that's quite the "nifty" element!
And 47.4% O? Oxygen, my dear friend! Always there to "take our breath away"!
Now, let's find the empirical formula. To do that, we need to determine the ratio of the elements in the compound.
First, we can assume we have 100 grams of the compound (just to make calculations easier).
So, we have 38.7 grams of K, 13.9 grams of N, and 47.4 grams of O.
To find the moles, we divide each mass by their respective atomic masses:
K: 38.7 g / 39.10 g/mol ≈ 0.990 mol
N: 13.9 g / 14.01 g/mol ≈ 0.992 mol
O: 47.4 g / 16.00 g/mol ≈ 2.963 mol
Now, we divide each mole value by the smallest mole value (which is 0.990):
K: 0.990 mol / 0.990 mol = 1 mol
N: 0.992 mol / 0.990 mol ≈ 1 mol
O: 2.963 mol / 0.990 mol ≈ 3 mol
Therefore, the empirical formula of the compound is KNO3 (1:1:3 ratio), which we can call... "Potassium Nitrate"!
I hope this empirical formula brings a smile to your face!
To find the empirical formula of the compound, we need to determine the ratio of the elements present in it.
Step 1: Convert the percentages to grams:
Given percentages:
K (Potassium) = 38.7%
N (Nitrogen) = 13.9%
O (Oxygen) = 47.4%
Assume a 100g sample:
K = 38.7g
N = 13.9g
O = 47.4g
Step 2: Convert the grams of each element to moles:
To convert grams to moles, we need to divide the mass of each element by its atomic mass.
Atomic mass of K = 39.10 g/mol
Moles of K = 38.7g / 39.10 g/mol = 0.989 mol
Atomic mass of N = 14.01 g/mol
Moles of N = 13.9g / 14.01 g/mol = 0.992 mol
Atomic mass of O = 16.00 g/mol
Moles of O = 47.4g / 16.00 g/mol = 2.96 mol
Step 3: Divide the moles of each element by the smallest number of moles:
To find the simplest whole number ratio, we divide the moles of each element by the smallest number of moles calculated in Step 2.
Smallest number of moles = 0.989 mol (for K)
Moles of K / Smallest number of moles = 0.989 mol / 0.989 mol = 1.000
Moles of N / Smallest number of moles = 0.992 mol / 0.989 mol = 1.003
Moles of O / Smallest number of moles = 2.96 mol / 0.989 mol = 2.994
Step 4: Determine the empirical formula using the whole number ratios:
The ratio of the elements is approximately K1N1O3. So, the empirical formula of the compound is KNO3.
To find the empirical formula of a compound, you need to determine the ratio of the elements present in the compound. Here's how you can do it:
Step 1: Convert the percentages to grams.
Since the percentages are given by mass, you can assume that you have 100g of the compound. Therefore, in this case, you have 38.7g of K, 13.9g of N, and 47.4g of O.
Step 2: Convert the grams to moles.
To convert grams to moles, you need to divide the mass of each element by its molar mass. The molar mass of an element is equal to the atomic mass of the element from the periodic table. The atomic masses of K, N, and O are approximately 39.1 g/mol, 14.0 g/mol, and 16.0 g/mol, respectively.
Using these values, you can calculate the number of moles for each element:
- K: 38.7g / 39.1 g/mol ≈ 0.99 mol
- N: 13.9g / 14.0 g/mol ≈ 0.99 mol
- O: 47.4g / 16.0 g/mol ≈ 2.96 mol
Step 3: Determine the ratio of the elements.
To find the simplest ratio of the elements, divide each of the mole values by the smallest one. In this case, the smallest mole value is approximately 0.99 mol (from K and N).
Dividing each of the moles by 0.99, you get:
- K: 0.99 mol / 0.99 mol ≈ 1 mol
- N: 0.99 mol / 0.99 mol ≈ 1 mol
- O: 2.96 mol / 0.99 mol ≈ 3 mol
Step 4: Write the empirical formula.
After determining the ratio of the elements, you can write the empirical formula using the whole-number ratio obtained. In this case, the ratio is K:N:O = 1:1:3.
Therefore, the empirical formula of the compound is KNO3.