Calculating the mass of solid needed
| c | = | n |
| V |
n = c × V
mol = mol
volumetric flask
m = n × M
g = mol × g mol–1
The concentration of a solution indicates the quantity of solute (substance dissolved) in a particular volume of solution.
A rearranged form of the equation above allows you to calculate the amount in moles of solute required to make up your standard solution.
For the standard solution c is the required concentration. What is V?
V is the volume of the volumetric flask in .
Note that the volume of these flasks is usually given in (like 250 ). This volume can be converted to by multiplying by 10–3 (250 × 10–3 ).
How is the calculated amount in moles related to the mass that I must weigh?
Chemists often use amount in moles (n) and volume (V) of the solution in to give the concentration unit . This is expressed mathematically at the right.
A rearranged form of the equation above allows you to calculate the amount in moles of solute required to make up your standard solution.
For the standard solution c is the required concentration. What is V?
V is the volume of the volumetric flask in .
Note that the volume of these flasks is usually given in (like 250 ). This volume can be converted to by multiplying by 10–3 (250 × 10–3 ).
How is the calculated amount in moles related to the mass that I must weigh?
As shown at the right, multiplying the calculated amount in moles (n) by the mass of one mole of the solute (M) gives the mass (m) of solute required.
The mass of one mole of solute (M) is calculated from the formula for the solute by adding the molar masses of the atoms. These are below the element symbol in the periodic table.
The mass of one mole of solute (M) is calculated from the formula for the solute by adding the molar masses of the atoms. These are below the element symbol in the periodic table.