Answer:
Yes.
Explanation:
"These starting substances of a chemical reaction are called the reactants, and the new substances that result are called the products."
There is a beginning product, and a reactant is needed in order for something to happen.
For example, according to Newton, something cannot happen until an exterior force comes and stops/pushes it.
Sorry if this is incorrect, I am just 4th grade :(
Answer:
38.7%
41.3%
20%
Explanation:
The percentage composition helps to know the what percent of the total mass of a compound is made up of each of the constituent elements or groups.
To solve this problem:
- find the formula mass by adding the atomic masses of the atoms that makes up the compound.
- place the mass contribution of the element or group to the formula mas and multiply by 100;
Compound:
Ca₃(PO₄)₂
Formula mass = 3(40) + 2[31 + 4(16)]
= 120 + 2(95)
= 120 + 190
= 310
%C = 
x 100 = 38.7%
%P = 
x 100 = 41.3%
%O = 
x 200 = 20%
Answer: 7
Explanation:
50 ml 0.125 M KOH = (50 * 0.125) = 6.25 ml 1 M KOH
similarly 50 ml 0.125 M HCl = 6.25 ml 1 M HCl
so KOH will fully neutralize the HCl so the pH of the medium will be 7
H+ + OH- = H2O
so Kw = [H=][OH-]
= [H+]^2 = 10-14
SO [H+] = 10-7
pH = -log [H+]
pH = -log[10-7]
pH = 7
Answer:
7. A) I, II
; 8. D) 2.34e9 kJ
Step-by-step explanation:
7. Combustion of ethanol
I. The negative sign for ΔH shows that the reaction is exothermic.
II. The enthalpy change would be different if gaseous water were produced.
That's because it takes energy to convert liquid water to gaseous water, and this energy is included in the value of ΔH.
III. The reaction is a redox reaction, because
- Oxygen is reacting with a compound
- The oxidation number of C increases
- The oxidation number of O decreases.
IV. The products of the reaction occupy a smaller volume than the reactants, because 3 mol of gaseous reactant are forming 2 mol of gaseous product.
Therefore, only I and II are correct.
7. Hindenburg
Data:
V = 2.00 × 10⁸ L
p = 1.00 atm
T = 25.1 °C
ΔH = -286 kJ·mol⁻¹
Calculations:
(a) Convert temperature to kelvins
T = (25.1 + 273.15) K = 298.25 K
(b) Moles of hydrogen
Use the <em>Ideal Gas Law</em>:
pV = nRT
n = (pV)/(RT)
n = (1.00 × 2.00 × 10⁸)/(0.082 06 × 298.25) = 8.172 × 10⁶ mol
(c) Heat evolved
q = nΔH = 8.172 × 10⁶ × (-286) = -2.34 × 10⁹ kJ
The hydrogen in the Hindenburg released 2.34e9 kJ
.
