Answer:
a) 48KJ
b) -48KJ
Explanation:
Given that;
ln(K2/K1) = ΔH°/R(1/T2 - 1/T1)
K2= equilibrium constant at T2
K1 = equilibrum constant at T1
R = gas constant
T1 = initial temperature
T2 = final temperature
When we double the equilibrium constant K1; K2 = 2K1
T1 = 310 K
T2 = 310 + 15 = 325 K
ln(2K1/K1) =- ΔH°/R(1/T2 - 1/T1)
ln2 = -ΔH°/8.314(1/325 - 1/310)
0.693 = -ΔH°/8.314(3.08 * 10^-3 - 3.2 * 10^-3)
0.693 = -ΔH°/8.314 (-0.00012)
0.693 = 0.00012ΔH°/8.314
0.693 * 8.314 = 0.00012ΔH°
ΔH° = 0.693 * 8.314/0.00012
ΔH° = 48KJ
b) K2 =K1/2
ln(K1/2/K1) =- ΔH°/R(1/T2 - 1/T1)
ln (1/2) = -ΔH°/8.314 (1/325 - 1/310)
-0.693 = -ΔH°/8.314 (-0.00012)
-0.693 = 0.00012ΔH°/8.314
-0.693 * 8.314 = 0.00012ΔH°
ΔH°= -0.693 * 8.314/0.00012
ΔH°= -48KJ
The first step is to find the number of moles of OH⁻ that reacted with the HCl. To do this multiply 2.00L by 1.50M to get 3 moles of Ca(OH)₂. Then you multiply 3 by 2 (there are 2 moles of OH⁻ per every 1 mole of Ca(OH)₂) to get 6 moles of OH⁻. That means that you needed 6 moles of HCl since 1 mole of HCl contains 1 mole of H⁺ and equal amounts H⁺ and OH⁻ reacted with each other. To find the molarity of the HCl solution you need to divide 6mol by 1L to get 6M. Tat means that the concentration of the acid was 6M.
I hope this helps. Let me know if anything was unclear.
Answer:
The number of electrons, in turn, determines the chemical properties of the atom. Protons contribute to the mass of an atom and provide the positive charge to the nucleus. The number of protons also determines the identity of the element
Calcium reacts gently with water to give hydrogen and calcium hydroxide, which is only slightly soluble, thus slows down the reaction.
It will be assumed that hydrochloric acid used is a dilute aqueous solution.
However, calcium reacts with hydrochloric acid to give calcium chloride which is readily soluble in water, and hydrogen, being a typical reaction of relatively active metals with acids.
Ca(s) + 2HCl(aq) -> CaCl2(aq) +H2(g) ↑ + heat
The clues that it is a chemical reaction could be:
- formation of a new substance, gaseous hydrogen
- disappearance of a metallic solid in the solution
- heat formed during the vigorous reaction.
As silver is below hydrogen in the electrochemical series, it will not be expected to react with dilute hydrocloric acid. (however, it dissolves in oxidizing acid such as nitric acid, but not displacing hydrogen as a product).
