Which of the clouds shown would indicate a possible future rain storm?

Determine the empirical formula of a compound having the following percent composition by mass: K: 24.74%; Mn: 34.76%; O: 40.50%

Dovator [93]

Answer: The empirical formula of the compound is $KMnO_4$

Explanation:

The empirical formula is the chemical formula of the simplest ratio of the number of atoms of each element present in a compound.

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

Let the mass of the compound be 100 g

Given values:

% of K = 24.7%

% of Mn = 34.76%

% of O = 40.50%

Mass of K = 24.7 g

Mass of Mn = 34.76 g

Mass of O = 40.50 g

To calculate the empirical formula of a compound, few steps need to be followed:

Step 1: Calculating the number of moles of each element

We know:

Molar mass of K = 39.10 g/mol

Molar mass of Mn = 54.94 g/mol

Molar mass of O = 16 g/mol

Putting values in equation 1, we get:

$\text{Moles of K}=\frac{24.7g}{39.10g/mol}=0.632 mol$

$\text{Moles of Mn}=\frac{34.76g}{54.94g/mol}=0.633 mol$

$\text{Moles of O}=\frac{40.50g}{16g/mol}=2.53 mol$

Step 2: Calculating the mole fraction of each element by dividing the calculated moles by the least calculated number of moles that is 0.632 moles

$\text{Mole fraction of K}=\frac{0.632}{0.632}=1$

$\text{Mole fraction of Mn}=\frac{0.633}{0.632}=1$

$\text{Mole fraction of O}=\frac{2.53}{0.632}=4$

Step 3: Writing the mole fraction as the subscripts of each of the element

The empirical formula of the compound becomes $K_1Mn_1O_4=KMnO_4$

Hence, the empirical formula of the compound is $KMnO_4$

4 0

3 years ago

5.40 g B determine the number of atoms

sdas [7]

Atomic mass Boron ( B ) = 10.811 u.m.a

10.811 g -------------- 6.02x10²³ atoms
5.40 g ----------------- ?? atoms

5.40 x ( 6.02x10²³) / 10.811 =

3.0069x10²³ atoms

4 0

3 years ago

Which of the following has the smallest atomic radius?

kari74 [83]

C. Beryllium. Which has 112 pm

4 0

4 years ago

Read 2 more answers

You have 2.394 x 102 mL of oxygen gas (O2) at 7.20 x 102 mm of Hg and 78 oC.

igomit [66]

We are given with
V = 2.394 x 102 mL
P = 7.20 x 102 mm of Hg
T = 78 oC

We are asked to determine the mass of the sample in milligrams
Using the ideal gas law
n = PV / RT
n = 7.20 x 102 mm of Hg (2.394 x 102 mL) / R (78 + 273)
Use the appropriate value for R or just convert the values to SI and use R = 8.314
Then, solve for the mass of the sample by using the MW Oxygen which is 16 g/mol

3 0

3 years ago

What is the wavelength of a 2.80 Hz wave?

s2008m [1.1K]

I attached the working and the answer to the question below.

Please note that in the formula, C = speed of light, ν = frequency, λ= wavelength

The wavelength of a 2.80 Hz wave is 1.07 × 10¹⁰ cm.

6 0

3 years ago