Answer:
Inert gases
Explanation:
Inert elements have a stable electron configuration meaning their shells/orbitals are full with their requisite number of electrons. Therefore, gaining or losing an electron would take high ionization energy. Therefore they are less likely to be involved in chemical reaction unless a high amount of energy is used. An example of an inert gas is Helium.
Note that
The heating value of standard coal is about 30,080 kJ/kg
1 L of water has a mass of 1.0 kg
The mass of 15 L of water = 15 kg.
The latent heat of vaporization of water is about 2260 kJ/kg,
The energy required to boil 15 L of water is
(2260 kJ/kg)*(15 kg) = 33900 kJ
The mass of coal required to provide this energy is
(33900 kJ)/(30080 kJ/kg) = 1.127 kg
Because 1 kg = 2.205 lb, the mass of coal required is
(1.127 kg)*(2.205 lb/kg) = 2.485 lb
Answer: 2.49 lb (nearest hundredth)
The heat lost by copper(ii) sulfate is equal to heat absorbed by water since the total energy in the system remains constant according to the law of conservation of energy.
<h3>How can the number of moles be determined?</h3>
The number of moles of a substance is determined using the formula below:
- Number of moles = mass/molar mass
Assuming the mass of copper(ii) sulfate used is <em>Mc</em>, number of moles of copper(ii) sulfate used is:
- Moles of copper(ii) sulfate = <em>Mc</em>/159.60 moles
The heat absorbed by water is calculated using the formula below:
- Quantity of Heat, H = mass × specific heat capacity × temperature change
mass of water <em>=</em><em> </em> 10 g
Let temperature change be <em>Tc</em>
Heat<em> </em>absorbed<em> </em>by water = 10 × 4.186 × Tc = 41
86Tc
The change in internal energy, ΔU of copper(ii) sulfate, is given as:
where:
Q = heat absorbed by water
W = work done by or on the system
The enthalpy of the reaction is given as:
- ΔH= energy released or absorbed/moles of copper (ii) sulfate
Therefore, according to the law of conservation of energy, the total energy in the system remains constant.
Learn more about internal energy change at: brainly.com/question/14126477
