Answer:
<em>293.99 g </em>
OR
<em>0.293 Kg</em>
Explanation:
Given data:
Lattice energy of Potassium nitrate (KNO3) = -163.8 kcal/mol
Heat of hydration of KNO3 = -155.5 kcal/mol
Heat to absorb by KNO3 = 101kJ
To find:
Mass of KNO3 to dissolve in water = ?
Solution:
Heat of solution = Hydration energy - Lattice energy
= -155.5 -(-163.8)
= 8.3 kcal/mol
We already know,
1 kcal/mol = 4.184 kJ/mole
Therefore,
= 4.184 kJ/mol x 8.3 kcal/mol
= 34.73 kJ/mol
Now, 34.73 kJ of heat is absorbed when 1 mole of KNO3 is dissolved in water.
For 101 kJ of heat would be
= 101/34.73
= 2.908 moles of KNO3
Molar mass of KNO3 = 101.1 g/mole
Mass of KNO3 = Molar mass x moles
= 101.1 g/mole x 2.908
= 293.99 g
= 0.293 kg
<em><u>293.99 g potassium nitrate has to dissolve in water to absorb 101 kJ of heat. </u></em>
Answer:
First, balance the half-reactions
Second, equalize the electrons
Third,add two reaction equations to get final answer
Explanation:
For example
H₂C₂0₄ + MnO⁻₄ ---------->CO₂+Mn²⁺
(i) Balancing the half reactions
H₂C₂O₄-------->2CO₂+2H⁺+2e⁻
5e⁻ +8H⁺+MnO₄⁻----------->Mn²⁺+4H₂O
(ii)
Equalizing the electrons
5H₂C₂O₄--------->10CO₂+10H⁺+10e⁻ ---here there is a factor of 5
10e⁻+16H⁺+2MnO₄⁻--------->2Mn²⁺+8H₂O -----here there is a factor of 2
(iii)
Add the two where electrons and some Hydrogen ions will cancel out
5H₂C₂O₄+6H⁺+2MnO₄⁻---->10CO₂+2Mn²⁺+8H₂O
pH value 1 represents a solution with the lowest OH⁻ion concentration.
<u>Explanation:</u>
pH is given by the expression as the negative logarithm to the base 10 of the concentration of hydrogen ions.
pH = -log₁₀[H⁺]
If the pH is lower than 7, pH < 7 then it is acidic
If the pH = 7, then it is neutral
If the pH > 7, then it is basic
If pH is 1 then the solution is showing mostly acidic character,which is least basic in its character.
So if the pH is 1, which is most acidic and least basic solution that is lowest OH⁻ ion concentration.
When it comes to physical changes like phase changes, there are two types of heat energy: sensible heat and latent heat. Sensible heat is the heat absorbed/released when you heat the substance but it doesn't change phase. An example would be heating lukewarm water. The substance is liquid all throughout. Latent heat, on the other hand, is the heat absorbed/released when there is a phase change. An example would be boiling water, because it changes liquid to vapor.
Hence, for freezing liquid, you use the latent heat, specifically the heat of fusion. The answer should be
2.5 g * (1 mol/18.02 g) * 6.03 kJ/mol = 0.84 kJ/mol
The answer is not in the choices. You only use Hvap if you boil water.
