Answer:
1 gram
Explanation:
Half life = 25 years
Starting mass = 16 grams
Time = 100 years
Number of half lives = Time / Duration of Half life = 100 / 25 = 4
After first Half life;
Remaining mass = 16 / 2 = 8 g
After Second Half life;
Remaining mass = 8 / 2 = 4 g
After Third Half life;
Remaining mass = 4 / 2 = 2 g
After Fourth Half life;
Remaining mass = 2 / 2 = 1 g
When the reaction equation is:
HF ↔ H+ + F-
and when the Ka expression
= concentration of products/concentration of reactions
so, Ka = [H+][F-]/[HF]
when we assume:
[H+] = [F-] = X
and [HF] = 0.35 - X
So, by substitution:
6.8 x 10^-4 = X^2 / (0.35 - X) by solving for X
∴ X = 0.015 M
∴[H+] = X = 0.015
when PH = -㏒[H+]
∴PH = -㏒0.015
= 1.8
1. Answer;
- Exothermic reaction
Explanation;
-Exothermic reactions are types of chemical reactions in which heat energy is released to the surroundings. Since enthalpy change is the difference between the energy of products an that of reactants. It means that in an exothermic reaction the energy of products is less than that of products. In this case an energy of 315kJ is released to the surroundings.
2. Answer;
Conserved
-The total amount of energy before and after a chemical reaction is the same. Thus, energy is conserved.
Explanation;
-According to the law of conservation of energy, energy is neither created nor destroyed. Energy may change form during a chemical reaction. For example, energy may change form from chemical energy to heat energy when gas burns in a furnace. However, the exact amount of energy remains after the reaction as before, which is true for all chemical reactions.
<u>Answer:</u> The amount of energy absorbed by water is 5390 Calories
<u>Explanation:</u>
To calculate the amount of heat absorbed at normal boiling point, we use the equation:
where,
q = amount of heat absorbed = ?
m = mass of water = 10 grams
= latent heat of vaporization = 539 Cal/g
Putting values in above equation, we get:
Hence, the amount of energy absorbed by water is 5390 Calories
Answer:
1. relative time
2.absolute time
Explanation:
Time that is measured in definite periods such as minutes, days, and years is called
a. Relative time.
b. absolute time.