Calculate the energy required to melt 12.4 g of ice at 0 oC.
The molar heat of fusion for ice is 6.02 kJ/mol.

Energy required is 4.147 kj.

Explanation:

Given data:

Mass of ice = 12.4 g

Temperature = 0°C

Molar heat fusion for ice = 6.02 kj/mol

Energy required to melt = ?

Solution:

Formula:

q = n ×ΔH

q = heat

n = number of moles

ΔH = enthalpy

First of all we will calculate the number of moles.

Number of moles = mass/ molar mass

Number of moles = 12.4 g/ 18 g/mol

Number of moles = 0.69 mol

Now we will put the values in formula.

q = n × ΔH

q = 0.69 mol × 6.02 kj/mol

q = 4.147 kj

Number of H atoms before balance = 2

Number of H atoms after balance = 4

Equalization of chemical reactions can be done using variables. Steps in equalizing the reaction equation:  

•1. gives a coefficient on substances involved in the equation of reaction such as a, b, or c, etc.  

•2. make an equation based on the similarity of the number of atoms where the number of atoms = coefficient × index (subscript) between reactant and product  

•3. Select the coefficient of the substance with the most complex chemical formula equal to 1  

For gas combustion reaction which is a reaction of hydrocarbons with oxygen produces CO₂ and H₂O (water vapor). can use steps:  

Balancing C, H and the last O  

Reaction

H₂S+3O₂⇒H₂O+2SO₂

If we only look at H atoms, then the number of H atoms on the right and left of the reaction is the same, which is 2.

But this equation is not yet balanced because the number of O atoms and S atoms are not the same, so it is necessary to give a coefficient so that both sides are equal

2H₂S+3O₂⇒2H₂O+2SO₂

The equation has been balanced, now the number of H atoms on the left and right of the reaction is equal to 4