The answer is B. a flashlight uses a battery to operate.
The battery represents the chemical energy. This is converted into electricity, which is converted into light energy.
Answer:
6. O₂ + Cu —> CuO
7. H₂ + Fe₂O₃ —> H₂O + Fe
8. O₂ + H₂ — > H₂O
9. H₂S + NaOH —> Na₂S + H₂O
10. Al + HCl —> H₂ + AlCl₃
Explanation:
6. Oxygen gas react with solid copper metal to form copper(II) oxide
Oxygen gas => O₂
Copper => Cu
copper(II) oxide => CuO
The equation is:
O₂ + Cu —> CuO
7. hydrogen gas and iron(III) oxide powder react to form liquid water and solid iron power
hydrogen gas => H₂
Iron(III) oxide => Fe₂O₃
Water => H₂O
Iron => Fe
The equation is:
H₂ + Fe₂O₃ —> H₂O + Fe
8. Oxygen gas react with hydrogen gas to form liquid water
Oxygen gas => O₂
hydrogen gas => H₂
Water => H₂O
The equation is:
O₂ + H₂ — > H₂O
9. Hydrogen sulphide gas is bubbled through a sodium hydroxide solution to produce sodium sulphide and liquid water
hydrogen sulphide => H₂S
sodium hydroxide => NaOH
Sodium sulphide => Na₂S
Water => H₂O
The equation is:
H₂S + NaOH —> Na₂S + H₂O
10. Hydrogen gas and aluminum chloride solutions are produced when solid aluminum react with hydrochloric acid
Aluminum => Al
Hydrochloric acid => HCl
hydrogen gas => H₂
Aluminum chloride => AlCl₃
The equation is:
Al + HCl —> H₂ + AlCl₃
Answer:
pH → 7.46
Explanation:
We begin with the autoionization of water. This equilibrium reaction is:
2H₂O ⇄ H₃O⁺ + OH⁻ Kw = 1×10⁻¹⁴ at 25°C
Kw = [H₃O⁺] . [OH⁻]
We do not consider [H₂O] in the expression for the constant.
[H₃O⁺] = [OH⁻] = √1×10⁻¹⁴ → 1×10⁻⁷ M
Kw depends on the temperature
0.12×10⁻¹⁴ = [H₃O⁺] . [OH⁻] → [H₃O⁺] = [OH⁻] at 0°C
√0.12×10⁻¹⁴ = [H₃O⁺] → 3.46×10⁻⁸ M
- log [H₃O⁺] = pH
pH = - log 3.46×10⁻⁸ → 7.46
C. 2 hydrogen (H) atoms because in bonding with them sulfur will get a full valence shell and hydrogen will have a full valence shell.
