Mass contribution of K = 3 x 39.10 = 117.30 g/mol Mass contribution of Fe = 1 x 55.85 = 55.85 g/mol Mass contribution of C = 6 x 12.01 = 72.06 g/mol Mass contribution of N = 6 x 14.01 = 84.06 g/mol Step 3: Find the total molecular mass of the molecule. The molecular mass is the sum of the mass contributions of each element. Simply add each mass contribution together to find the total. Molecular mass of K 3 Fe(CN) 6 = 117.30 g/mol + 55.85 g/mol + 72.06 g/mol + 84.06 g/mol Molecular mass of K 3 Fe(CN) 6 = 329.27 g/mol Step 4: Find the mass percent composition of each element. To find the mass percent composition of an element, divide the mass contribution of the element by the total molecular mass.

This number must then be multiplied by 100% to be expressed as a percent. Mass percent composition of K = mass contribution of K/molecular mass of K 3 Fe(CN) 6 x 100% Mass percent composition of K = 117.30 g/mol/329.27 g/mol x 100% Mass percent composition of K = 0.3562 x 100% Mass percent composition of K = 35.62% Mass percent composition of Fe = mass contribution of Fe/molecular mass of K 3 Fe(CN) 6 x 100% Mass percent composition of Fe = 55.85 g/mol/329.27 g/mol x 100% Mass percent composition of Fe = 0.1696 x 100% Mass percent composition of Fe = 16.96% Mass percent composition of C = mass contribution of C/molecular mass of K 3 Fe(CN) 6 x 100% Mass percent composition of C = 72.06 g/mol/329.27 g/mol x 100% Mass percent composition of C = 0.2188 x 100% Mass percent composition of C = 21.88% Mass percent composition of N = mass contribution of N/molecular mass of K 3 Fe(CN) 6 x 100% Mass percent composition of N = 84.06 g/mol/329.27 g/mol x 100% Mass percent composition of N = 0.2553 x 100% Mass percent composition of N = 25.53% The Answer. K 3 Fe(CN) 6 is 35.62% potassium, 16.96% iron, 21.88% carbon and 25.53% nitrogen. If you add up all the mass percent compositions, you should get 100%.35.62% + 16.96% + 21.88% + 25.53% = 99.99%Where is the other .01%? This example illustrates the effects of significant figures and rounding errors. This example used two significant figures past the decimal point. Here you will our reverse percentage calculator which will help you to find the original number before a percentage increase or decrease. Our calculators will not only find the original numbers, but also show you all the working out along the way! This calculator will help you to find the original number , when you have been given the final number and the percentage of the original number that made it.

if you know that 70% of a number is 210 then it will find the original number. (Answer: 300) Simply enter the final number in the first box and the percentage in the 2nd box. Click on the 'Find Original Number' box to work out what the original number was! This calculator will help you to find the original number, when you have been given the final number and the percentage increase or decrease. Example: if a toy in a sale marked 20% off costs $210, what is the original price. (Answer: $262.50) Simply enter the final number in the first box and the percentage in the 2nd box and whether it was increased or decreased. Click on the 'Find Original Number' box to work out what the original number was! Read on below if you want to find out how to find out reverse percentages work. Reverse percentages are used when the percentage and the final number is given, and the original number needs to be found. If the percentage is an increase then add it to 100, if it is a decrease then subtract it from 100. Step 2) Divide the percentage by 100 to convert it to a decimal. Step 3) Divide the final number by the decimal to get back to the original number. Step 1) The percentage of the original number is 35% Step 2) Convert percent to a decimal: 35% = 35 ÷ 100 = 0.35. Steo 3) Divide final number by decimal: 320 ÷ 0.35 = 914.2857. Example 2) A car is reduced by 20% in price to $40,000. Step 1) The percentage of the original number is 100 - 20 = 80% Step 2) Convert percent to a decimal: 80% = 80 ÷ 100 = 0.8. Step 3) Divide final number by decimal: 40,000 ÷ 0.8 = 50,000. Five years later, she sells them for $7200 at a profit of 25% of their original value. Step 1) The percentage of the original number is 100 + 25 = 125% Step 2) Convert percent to a decimal: 125% = 125 ÷ 100 = 1.25. Step 3) Divide final number by decimal: 7200 ÷ 1.25 = 5760. Take a look at some more of our resources similar to these. Our online percentage practice zone gives you a chance to practice finding percentages of a range of numbers. You can choose your level of difficulty and test yourself with immediate feedback! This is the calculator to use if you want to find a percentage of a number. Simple choose your number and the percentage and the calculator will do the rest. If you need to find the percentage increase/decrease between 2 numbers, then this calculator is the one you need.

Simple input the original number, then the new number and the calculator will tell you the percentage increase or decrease. If you need to convert a percentage to a fraction - either a decimal fraction or a fraction in its simplest form, then use this calculator. You can also use the fraction to percentage calculator for converting any fraction into a percentage. This calculator takes a percentage and converts it at the click of a button. We have a wide range of free math calculators to help you. Most of our calculators show you their working out so that you can see exactly what they have done to get the answer. Our calculator hub page contains links to all of our calculators! Follow these 3 easy steps to get your worksheets printed out perfectly!

Follow these 3 easy steps to get your worksheets printed out perfectly! The Math Salamanders hope you enjoy using these free printable Math worksheets and all our other Math games and resources. We welcome any comments about our site or worksheets on the Facebook comments box at the bottom of every page. Edge from Plexus looks to be the answer to every individual’s daily energy crisis. In case you weren’t aware the entire world is in an energy crisis !