Gold has a latent heat fusion of 64.5 j/g. how much energy is required to melt 20.0 g of gold?

The amount of heat require to melt the gold is 1290 J.

Explanation:

Formula:

Q = m × Lf

Q = heat required to melt the substance

m = mass of given substance

Lf = Latent heat of fusion

Given data:

Lf = 64.5 j/g

m = 20 g

Q = ?

Now we will put the values in formula.

Q = m × Lf

Q =  20 g × 64.5 j/g

Q = 1290 J

The amount of heat require to melt the gold is 1290 J.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"