2. How many joules are
required to change the temperature of 120 ml of
water by 5 °C?

Energy required : 2508 J

Further explanation

Given

V= 120 ml

Δt = 5°C

Required

Heat needed

Solution

Heat can be formulated :

Q = m.c.Δt

m = mass, g  

c = specific heat, joules / g °C  (water=4.18 J.g °C)

∆T = temperature difference, ° C / K  

mass water = 120 g(density = 1 g/ml)

Input the value :

Q = 120 g x 4.18 J.g °C x 5 °C

Q = 2508 J

  the volume of  0.220 m k2s    solution  required  to  completely  react with 175 ml  of 0.115m co(no3)2  calculate the moles  of co(no3)2 =  molarity x volume/1000175 x0.115/1000= 0.02  moleswrite  the reacting  equationk2s(aq)  +  co(no3)2  = 2 kno3(aq)  + cos(s)by  use  of mole ratio between k2s to co(no3)2 which  is  1: 1 the moles of k2s is therefore = 175  x0.115/1000= 0.02  molesvolume = moles/molarity=0.02/0.22=0.09  ml  of k2s