Conversion of mass volume concentration and percentage concentration

Conversion of mass volume concentration and percentage concentration

The meaning of the title is as follows:
The conversion problem between mass volume percentage concentration and mass mass mass percentage concentration
There is a quantitative relationship between them, so "density" is needed
Suppose that the density of the solution is "ρ", and the unit is g / ml, then the conversion formula is as follows:
C% (solute mass m / solution volume V)
=%(solute mass m / solution density ρ * solution volume V)
=%(mass of solute M / mass of solution m)

How to convert mass volume concentration into g / L
When preparing the medium, the book says to add 2% starch. How much g / L is that?

This is a common problem in biology. We have to use a balance. My friend, the biology teacher in our school asked me this question

How to convert the relationship between mass concentration (%) and mass volume concentration (g / L)?
Do you need to know other parameters, such as density, then their relationship is?
For example, 180g / L of a substance, its mass fraction, that is, the unit is% (how many grams of solute / how many grams of solution). If required, the density is 1234kg / m3.

Without the parameter of density, you can calculate directly. 5% sugar, when you prepare this solution, you must be 5g sugar + 95g water. That is 5g / 100mL, and then change it to L. strictly speaking, it will involve mole