Question

. What is the % w/w concentration for a solution that contains 100.0 g of water and 3.45 g of solute?

Answer 1

Answer:

Explanation:A solution is a homogeneous mixture of two or more chemical substances. If we have a solution

made from a solid and a liquid, we say that the solid is dissolved in the liquid and we call the

solid the solute and the liquid the solvent. Initially, we will consider only solutions of a solid in

water. If a solution has a small amount of solute in a large amount of solvent, we say that the

solution is dilute (or that we have a dilute solution). If a solution has a large amount of solute

for a certain amount of solvent, we say that the solution is concentrated (or that we have a

concentrated solution). We see that the terms dilute and concentrated are not precise and are

merely used to give a rough indication of the amount of solute for a given amount of solvent.

The amount of solute in a given amount of solvent (or solution) is called the concentration of

the solution. In this course, we will consider two ways of expressing concentration - mass

percent and molarity. We will consider molarity here and mass percent later

Molarity

The molarity of a solution (or, more precisely, of a solute in a solution) is the number of moles

of the solute in 1 litre of the solution.

molarity = M = N.B.: n = moles (solute)

litres (solution)

n

V(L)

mass (g)

MM

(MM = molar mass ≡ MW or FW)

The equation can also be used to find n (the number of moles of solute) if M (the molarity) and

V (the volume in litres) are known, and V if n and M are known.

n = MV V =

n

M

Answer 2

The concentration w/w % means (weight of solute/ weight of the solution)%.

This type of concentration does not depend on the temperature applied. As, it does not have a volume term involved in it.

In the given question

The weight of solute=3.45 g

The weight of solvent=100.00 g

The weight of solution= 103.45 g

w/w % concentration = weight of solute/ weight of solution%

w/w % concentration = 3.45/103.45

  = 3.33%

So, the w/w % concentration  of solution is 3.33%.