Question

Determine the number of moles and the amount in gm of NaOH in 250cm3 of a 0.100 M NaOH solution.

Answer 1

Hello Friend.

Here is your answer.
According to the questions , the given factors are:-

Molarity = Mass/ Molar mass x (1/1000) 

so for 250 ml of solution = mass / molar mass (250/1000)
Number of moles of NaOH in 250cm³ = 0.100 x$\frac{250}{1000}$ 
Hence the N. of moles of NaOH in 250cm³ = 0.025
Now , Mass of NaOH in 250cm³ = Number of moles x molar mass of NaOH

{Molar mass of NaOH = 23 + 16 + 1 =40 }

Hence mass of NaOH in 250cm³ = 0.025 x 40
=1

Hence 1 g of NaoH is required to prepare 0.100 M of solution.

Hope it Helps.
Have a nice day :-)                                              

Answer 2

Answer:

1g

Explanation:

molarity=moles÷Vol in litre

molarity=mass÷molar mass÷Vol in litre-( eq:1)

molar mass = 40(Naoh)

Vol=250cm3 to l

=0.25 l

molarity= 0.1 (given)

let's substitute these values in (eq:1)

0.1= mass÷40÷0.25

0.1=mass/40×1/0.25(simple division)

0.1=mass/40×0.25

0.1=mass/10

mass=0.1×10

mass=1g