Percent by Weight Formula

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Solutions and Percent Weight Change Formula

There are various features of solutions, including molarity, normality, molality, and percent by weight formula. Representation of solutions as a relative percentage concentration of solute in the given solution is one of the most popular and preferred methods, and it has various benefits. A solute is a minor component of the solution dissolved in solvent (the major part). The solute composition and the solution's composition are required to calculate the percentage by weight formula.

Percent Weight Change Formula 

Here are some ways in which the percent weight change formula is represented:


We express a solution's volume concentration as %v/v, also known as volume per volume; here, both solute and solvent in a solution are in liquid form. For example, 50ml sulphuric acid getting diluted in 50ml water is represented as sulphuric acid 50% v/v.


This percent by weight formula represents any solution expressed as %w/w, meaning weight by weight; here, we only consider the weight of any solution's components. For example: if 100g solution contains 30g HCl and 70g water, we express it as hydrochloric acid 30% w/w.


This percentage weight by volume formula is expressed as %w/v, meaning weight per volume, also known as m/v. For example: if we use 1g Potassium Iodide for making 100ml solution, it is represented as 1%w/v solution of KI.

Defining Solution

A solution refers to a homogeneous mixture of two or many compounds with the particle size being lesser than 1nm. 

Common ways of describing the Solution

Solutions are commonly described in various ways, which are as follows:

  1. Molarity – 

It means the number of moles of substance per liter in the solution.

  1. Normality –

It is the number of gram equivalents per liter volume of the solution.

  1. Molality – 

Molality is the number of solute moles per Kg of solution.

  1. Percentage Concentration of Solute in any Solution (percentage weight by volume formula) – 

The mass of solute in per ml volume of solution * 100. It is represented as follows:

(Mass of Solute(g) / Volume of Solution(ml) ) *100


We represent all of the percentage types by making some slight changes to the standard method of calculating percent weight by volume, i.e., (solute's mass (g) / Solution volume (ml) ) *100. For calculating percent weight by weight, we take both numerator and denominator by their weight, and for calculating percent volume by volume, both are taken by their volumes.

FAQ (Frequently Asked Questions)

Q1: Define Solute and Solvent in a Solution.

A1: A solute is a component that is in lower quantity and is dissolved in the solvent.

A solvent is in higher quantity which is used for dissolving the solute for a solution's formation.

For example: in the solution of tincture of Iodine (Iodine mixture in alcohol), Iodine is the solute, and alcohol is the solvent.

Q2: What are the Ways to represent the percent Weight Change Formula?

A2: Percent weight change formula can be represented using the following methods:

  1. %v/v - In this method, only volumes of solute and solution are considered

  2. %w/w - In this method, only weights of solute and solution are considered

  3. %w/v - In this method, the weight of the solute is considered whereas the volume of the solution is considered.

Q3: Mention the most common Ways for describing a Solution.

A3: We can describe a solution in terms of its components by calculating the following:

  1. Molarity

  2. Normality

  3. Molality

  4. Percent by weight : %v/v, %w/w, %w/v