Answer:
C. naturally uncombined with other elements.
Explanation: Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air.
Answer:
- 1.22KJ
Explanation:
First we put down the equation of the reaction;
NH4Cl(s)<-------->NH3(g) + HCl(g)
The equilibrium constant K is obtained from;
K= P(NH3) × P(HCl)
Where;
P(NH3)= pressure of ammonia
P(HCl)= pressure of hydrogen chloride gas
Pure solids and liquids are not included in the equilibrium constant expression. This is because they do not affect the reactant amount at equilibrium in the reaction, so they are disregarded and kept at 1. Remember that the activity, a, of any solid or liquid in a reaction is equal to 1. Hence [NH4Cl]= 1
K= 1.03 × 1.18 = 1.22
∆G° = -RTlnK
R= 8.314 JK-1mol-1
T= 465°C +273= 738K
K= 1.22
lnK= ln(1.22)= 0.19885
∆G= -(8.314 ×738 ×0.19885)
∆G= -1220.1 J
∆G= -1.22×10^3 J
∆G= - 1.22KJ
Answer:
for the force that sent the person forward, there is an equal force pushing back on the skateboard
Answer:
1.58x10⁻⁵
2.51x10⁻⁸
0.0126
63.10
Explanation:
Phenolphthalein acts like a weak acid, so in aqueous solution, it has an acid form HIn, and the conjugate base In-, and the pH of it can be calculated by the Handerson-Halsebach equation:
pH = pKa + log[In-]/[HIn]
pKa = -logKa, and Ka is the equilibrium constant of the dissociation of the acid. [X] is the concentrantion of X. Thus,
i) pH = 4.9
4.9 = 9.7 + log[In-]/[HIn]
log[In-]/[HIn] = - 4.8
[In-]/[HIn] =
[In-]/[HIn] = 1.58x10⁻⁵
ii) pH = 2.1
2.1 = 9.7 + log[In-]/[HIn]
log[In-]/[HIn] = -7.6
[In-]/[HIn] =
[In-]/[HIn] = 2.51x10⁻⁸
iii) pH = 7.8
7.8 = 9.7 + log[In-]/[HIn]
log[In-]/[HIn] = -1.9
[In-]/[HIn] =
[In-]/[HIn] = 0.0126
iv) pH = 11.5
11.5 = 9.7 + log[In-]/[HIn]
log[In-]/[HIn] = 1.8
[In-]/[HIn] =
[In-]/[HIn] = 63.10
Water Forms Strong Hydrogen bonds Would be your answer Also like the person said before me