FAQ

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 (w/w％)	Specific gravity (20℃)	Concentration (mol/L)	Equivalent	Normality (N)
Hydrochloric acid	HCl	36.46	20%	1.10	6.0	1	6.0
			35%	1.17	11.2		11.2
Nitric acid	HNO3	63.01	60%	1.37	13.0	1	13.0
			65%	1.39	14.3		14.3
			70%	1.41	15.7		15.7
Sulfate	H2SO4	98.08	100%	1.83	18.7	2	37.3
Phosphoric acid	H3PO4	98.00	85%	1.69	14.7	3	44.0
			90%	1.75	16.1		48.2
Acetate	CH3COOH	60.05	100%	1.05	17.5	1	17.5
Perchloric acid	HClO4	100.46	60%	1.54	9.2	1	9.2
			70%	1.67	11.6		11.6
Hydrogen peroxide water	H2O2	34.01	30%	1.11	9.8	-
			35%	1.13	11.6
Ammonia water	NH3	17.03	25%	0.91	13.4	1	13.4
			28%	0.90	14.8		14.8

【Quick reference of concentration and unit】

●How to express concentration of solution

Expression	Commentary
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

●ppmConversion table

ppb	ppm	%	mg/g	mg/L
1,000	1	0.0001	0.001	1
10,000	10	0.001	0.01	10
100,000	100	0.01	0.1	100
1,000,000	1,000	0.1	1	1,000
10,000,000	10,000	1	10	10,000