Question

QUESTION 12 What is the molarity of a solution made by diluting 37.5 mL of a 1.75 M HCl solution to 125.0 mL? O 0.525 M 5.25 M 5.83 M 2.68 M QUESTION 13 Match the following to the correct TYPE of reaction

Answer 1

Q 12)

You can use,

N₁ V₁ = N₂V₂

N₁= 1.75 M, (initial Molarity)

V₁= 37.5 mL ( initial volume)

N₂= ? ( final Molarity )

V₂ = 125 mL (Final volume)

by putting values we can calculate change in Molarity of HCl solution,

1.75 x 37.5 = N₂ x 125

so, N₂= (1.75 x 37.5 /125)

=0.525M

so correct answer is option 1)

7) solution -

a) Copper kettle ways 1.06 kg (specific heat of copper is 0.384J/g^{$\small \circ$}C

As you know mass of kettle should converted into grams from kg..

1.06 x 1000= 1060 gm

By putting values ,

Heat capacity of kettle in J/^{$\small \circ$}C =( 1060 g x 0.384 J/g^{$\small \circ$} C)

= 407 J/ ^{$\small \circ$} C

b) Temperature raised from 21.3 ^{$\small \circ$} C to 98.3^{$\small \circ$}C, so

$\small \Delta$T = 98.3-21.3 =77 ^{$\small \circ$} C

We know that amount of heat require =

q = m x C x  $\small \Delta$T

By putting values

q = heat supplied,  

q = 1060 g x 0.384 J/ g ^{$\small \circ$} C x 77 ^{$\small \circ$} C

= 31342 J

c) specific heat capacity of water = 4.18 J/g ^{$\small \circ$} C

# Change in temperature = 77 ^{$\small \circ$} C

# amount of water in = 1.15 liter

# density of water = 0.997 g/mL

We can calculate mass of water by using density =

Mass = density x volume

= 0.997 g/mL x 1.15 L

=1.1465 kg

But we have to convert mass into grams by multiplying 1000,

Mass = 1.146 x 1000

=1146.5 g

By putting values into formula-

q = m X C x $\small \Delta$ T

= 1146.5 g x 4.18 J / g ^{$\small \circ$} C x 77 ^{$\small \circ$} C

= 369012 J