Formulas you need to know for Exam #1



Formulas you need to know for Exam #1

1. Density

Density is mass divided by volume:

[pic]

2. Percent by mass

If a mixture contains some component, the % by mass of that component is calculated by dividing the mass of the component by the total mass of the mixture and multiplying by 100%:

[pic]

3. Percent composition from the molecular formula

The percent composition of some element in a molecular formula is calculated by multiplying the number of atoms of that element by its atomic weight, dividing the product by the total molecular weight of the compound, and multiplying by 100%:

[pic]

4. Relation between the mass of a compound, its molar mass, and the number of moles

[pic]

[pic]

5. Percent by mass of solute (percent concentration)

To find percent by mass of solute, divide the mass of solute (dissolved substance) by the total mass of the solution, and multiply the obtained number by 100%:

[pic]

6. Molarity (molar concentration)

To find the molarity of a solution, divide the number of moles of solute (dissolved substance) by the total volume of the solution:

[pic]

7. Dilution of solutions

If solution of molarity M1 and volume V1 is diluted to molarity M2 and volume V2, the following relation can be used:

[pic]

Use this formula only for dilution of solutions. DO NOT use it for chemical reactions!

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download