How To Know Chemical Compound Makeup Given Weight Precentage

Summate mass, concentration and pH of solutions

In this tutorial, we are going to do some bug which contains relationship of mass, concentration and pH in solutions. You can empathise how to apply those equations in such problems to practise these type of questions easily.

Question i

Summate the NaOH weight required to prepare 500ml of NaOH solution of pH=13. Room temperature is 25⁰C.

Calculate concentration of solution of known pH

Calculate pOH from pH by using the pH + pOH = xiv (at 25⁰C)
Then you can calculate the concentration of NaOH solution by pOH = -log₁₀[OH^- _(aq)] .
So find the required moles of NaOH past the equation of C =due north/v . Here C = concentration, n=required moles, five = volume of solution
Now weight is measured by multiplying number of moles and molar mass.

Assumptions

The OH^- received from water dissociation is negligible when information technology compares with OH^- received from NaOH.

calculate weight concentration of solution

Calculate pOH from pH value

pH + pOH = 14
13 + pOH = 14
pOH = 1

Calculate concentration (in mol dm^-3) of solution

Now nosotros know the pOH of NaOH solution. Employ the relation of pOH and OH^- concentration to summate the concentration of OH^-.

pOH = -log₁₀[OH^- _(aq)]
1 = -log₁₀[OH^- _(aq)]
[OH^- _(aq)] = 0.1 mol dm^-3

Discover the required moles of NaOH

Concentration, moles amount, and volume relation is used.

C = n/five
0.1 = northward/0.five [500 ml = 0.v dm³]
n = 0.05mol

NaOH amount = 0.05 mol

Find the required weight(g)

Multiply required moles times molecular weight

m = mass
northward = moles
G = molecular weight
n = one thousand/M

m = molecular weight * moles
m = Thou*n
m = 0.05 * forty
m = 2g

How to summate mass given ph and volume of a solution?

Ok. First we should know, what are the known parameters of the given solution. In this instance, pH and volume are given as data.

When pH value is known, concentration of H_threeO₊ or OH_- can be foundfrom pH or pOH equation.

According to the H₃O₊ or OH_- concentration and stoichiometric ratio of dissociation of the chemical compound, the concentration of dissolved compound is found.

With plant concentration and volume of solution, dissolved amount is found.

Amount = concentration * volume

Next, nosotros use human relationship of corporeality, mass and molecular mass.

Amount = mass / molecular mass

Because nosotros know the amount and molecular mass, dissolved mass tin be institute.