QHow to calculate the molar concentration of the solution
The molar concentration unit [mol/ L (M)] is a conventionally widely used as concentration method. It is the number of moles of target substance (solute) dissolved in 1 liter of solution. Here is how to calculate the concentration.
(Weight of 1 liter solution) x (purity) ÷ molecular weight
[Specific gravity of solution (g/mL) x 1,000 (mL) x Purity (w/w%) /100 ÷ Molecular weight]
For example, let's calculate the molar concentration of 2-mercaptoethanol (HSCH2CH2OH). The necessary information is as follows.
- Specific gravity (or density) = 1.114 g/mL
- Purity (or content) = 100 w/w% (assumed)
- Molecular weight = 78.13
By calculating this value by applying this value to the above equation, you can know the molar concentration.
1.114 g/mL x 1,000mL x 100w/w%/100 ÷ 78.13 = 14.26mol/L
In order to caluculate the concentration like above, it is necessary to know three points of "specific gravity (or density)", "purity (or content)" and "molecular weight". The table below is a quick reference chart of common acid and base concentrations. In acid and alkali, there is a use for "neutralization titration", "normality (N)" is often used.
【Quick reference chart of common acid and base concentrations】
|Compound||Molecular formula||Molecular weight||Purity
|Hydrogen peroxide water||H2O2||34.01||30%||1.11||9.8||-|
【Quick reference of concentration and unit】
●How to express concentration of solution
|Weight percent concentration||"g number" of solute in 100g solution. Expressed as w/w%, wt%, and % for density in many cases.|
|Volume percent concentration||"m number" of solute in 100m solution. Expressed as v/v% when mixture or solute is liquid.|
|Weight versus volume percent concentration||"g number of solute in 100m of solution. Expressed as w/v%.|
|Normality||Gram equivalent number of solute in 1L solution. Expressed as N for capacity analysis.|
|Volume specific concentration||Concentration indirectly expressed by the volume ratio of diluting the liquid reagent. It is used in JIS and others.
Example: Sulfuric acid (1 + 2) → Sulfuric acid is shown diluted with 2 volumes of water.
|Weight ratio concentration||Concentration indirectly expressed by weight ratio at which solid reagent is dissolved. It is used in JIS and others.
Example: Sodium chloride (1 + 19) →Dissolved in 19 weight of water with respect to 1 of NaCl.
|Molarity||Mol number of target substance (solute) in 1L of solution. Expressed as mol/ or M.|
●Prefix representing multiple
|Express bigness||Express smallness|
|100 =102||h（Hecto）||1/100 =10-2||c（Centi）||％（Percent）|
|1000 =103||k（Kilo）||1/1000 =10-3||m（Milli）||‰（Permili）|
|100万 =106||M（Mega）||1/100万 =10-6||μ（Micro）||ppm|
|1 Billion =109||G（Giga）||1/10Billion =10-9||n（Nano）||ppb|
|1 Trillion =1012||T（Tera）||1/1 Trillion =10-12||p（Pico）||ppt|
|1000 Trillion =1015||p（Peta）||1/1000 Trillion =10-15||f（Femto）||ppq|