Find the Mass Percentages K_2Cr_2O_7

$K_{2} C r_{2} O_{7}$

Step 1

To find the mass of $1$ mole of $K_{2} C r_{2} O_{7}$ look up the atomic mass of each element and multiply it by the number of atoms contained in each element in the molecule.

mass of $1$ mole of $K_{2} C r_{2} O_{7}$ $=$ $2 (mass of K)$ + $2 (mass of Cr)$ + $7 (mass of O)$

Step 2

Fill in the atomic masses from the periodic table.

mass of $1$ mole of $K_{2} C r_{2} O_{7}$ $=$ $2 (39.09999847)$ + $2 (52)$ + $7 (16)$

Step 3

Simplify the result.

Simplify each term.

Multiply $2$ by $39.09999847$ .

mass of $1$ mole of $K_{2} C r_{2} O_{7} = 78.19999694 + 2 (52) + 7 (16) g$

Multiply $2$ by $52$ .

mass of $1$ mole of $K_{2} C r_{2} O_{7} = 78.19999694 + 104 + 7 (16) g$

Multiply $7$ by $16$ .

mass of $1$ mole of $K_{2} C r_{2} O_{7} = 78.19999694 + 104 + 112 g$

Simplify by adding numbers.

Add $78.19999694$ and $104$ .

mass of $1$ mole of $K_{2} C r_{2} O_{7} = 182.19999694 + 112 g$

Add $182.19999694$ and $112$ .

mass of $1$ mole of $K_{2} C r_{2} O_{7} = 294.19999694 g$

Step 4

Find the mass percentage of $K$ .

The mass composition percentage is the mass of $K$ divided by the mass of the entire molecule converted to a percentage.

Mass percentage of $K = \frac{78.2}{294.19999694} \cdot 100$

Divide $78.2$ by $294.19999694$ .

$0.26580557 \cdot 100$

Multiply $0.26580557$ by $100$ .

$26.58055771$

Set the number as a percent.

Mass percentage of $K = 26.58055771 %$

Step 5

Find the mass percentage of $C r$ .

The mass composition percentage is the mass of $C r$ divided by the mass of the entire molecule converted to a percentage.

Mass percentage of $C r = \frac{104}{294.19999694} \cdot 100$

Divide $104$ by $294.19999694$ .

$0.35350102 \cdot 100$

Multiply $0.35350102$ by $100$ .

$35.35010233$

Set the number as a percent.

Mass percentage of $C r = 35.35010233 %$

Step 6

Find the mass percentage of $O$ .

The mass composition percentage is the mass of $O$ divided by the mass of the entire molecule converted to a percentage.

Mass percentage of $O = \frac{112}{294.19999694} \cdot 100$

Divide $112$ by $294.19999694$ .

$0.3806934 \cdot 100$

Multiply $0.3806934$ by $100$ .

$38.06934097$

Set the number as a percent.

Mass percentage of $O = 38.06934097 %$

Step 7

Find the mass percentage of each element in the molecule.

Mass percentage of $K = 26.58055771 %$

Mass percentage of $C r = 35.35010233 %$

Mass percentage of $O = 38.06934097 %$

Find the Mass Percentages K_2Cr_2O_7

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