B. is positive
H20 (l)--> H20 (g)
when that happens, the heat is absorbed into the liquid to change the state of the liquid to gas; therefore, in order to change to a gaseous state, heat must be a reactant. and so enthalpy is increasing
Answer:
Explanation:
A foam coffe cup is considered a perfectly insulated system: heat energy is not exchanged with the surroundings.
Under that assumption, the heat released by the chemical reaction is equal to the heat absorbed by the system.
1. Heat absorbed by the system:
Use the equation Heat = Q = m × C × ΔT, with:
- m = 126 g (the amount of solution produced)
- C = specific heat of pure water = 4.186 J/gºC
- ΔT = increase of temperature = 24.70 ºC - 21.00ºC = 3.70ºC
Q = 126g × 4.186J/gºC × 3.70ºC = 1,951.5J
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<em><u>2. Enthalpy of the reaction</u></em>
The enthalpy must be reported in kJ/mol.
Then, convert juoles to kilojoules, dividing by 1,000; and divide by 2.00 moles, which is the amount of compound that reacted:
- ΔHrxn = 1,951.5J × (1kJ / 1,000J) × (1 / 2mol) ≈ 0.9758 kJ/mol
Round to <em>3 significant figures</em>: 0.976 kJ/mol
Answer:
the water concentration at equilibrium is
⇒ [ H2O(g) ] = 0.0510 mol/L
Explanation:
- CH4(g) + H2O(g) ↔ CO(g) + 3H2(g)
∴ Kc = ( [ CO(g) ] * [ H2 ]³ ) / ( [ CH4(g) ] * [ H2O(g) ] ) = 0,30
⇒ [ CO(g) ] = 0.206 mol / 0.778 L = 0.2648 mol/L
⇒ [ H2(g) ] = 0.187 mol / 0.778 L = 0.2404 mol/L
⇒ [ CH4(g) ] = 0.187 mol / 0.778 L = 0.2404 mol/L
replacing in Kc:
⇒ ((0.2648) * (0.2404)³) / ([ H2O(g) ] * 0.2404 ) = 0.30
⇒ 0.0721 [ H2O(g) ] = 3.679 E-3
⇒ [ H2O(g) ] = 0.0510 mol/L