B. The surface of a silver cup turns black when it is exposed to air.
Answer : The total change in enthalpy of this reaction is 25 kJ.
Explanation :
Enthalpy of reaction : It is defined as the changes in heat energy takes place when reactants go to products. It is denotes as .
ΔH = Energy of product - Energy of reactant
ΔH is positive when heat is absorbed and the reaction is endothermic.
ΔH is negative when heat is released and the reaction is exothermic.
In the given potential energy diagram, the energy of product at higher level and energy of reactant at lower level. The ΔH for this reaction will be positive.
Given:
Energy of product = 55 kJ
Energy of reactant = 30 kJ
ΔH = Energy of product - Energy of reactant
ΔH = 55 kJ - 30 kJ
ΔH = 25 kJ
Thus, the total change in enthalpy of this reaction is 25 kJ.
Answer:
Double displacement reaction
Explanation:
Chemical equation:
H₃PO₄ + NaBr → HBr + Na₃PO₄
Balanced chemical equation:
H₃PO₄ + 3NaBr → 3HBr + Na₃PO₄
Step one:
H₃PO₄ + NaBr → HBr + Na₃PO₄
On left side of equation On right side pf equation
H = 3 H = 1
P = 1 P = 1
O = 4 O = 4
Na = 1 Na = 3
Br = 1 Br = 1
Step 2:
H₃PO₄ + NaBr → 3HBr + Na₃PO₄
On left side of equation On right side pf equation
H = 3 H = 3
P = 1 P = 1
O = 4 O = 4
Na = 1 Na = 3
Br = 1 Br = 3
Step 3:
H₃PO₄ + 3NaBr → 3HBr + Na₃PO₄
On left side of equation On right side pf equation
H = 3 H = 3
P = 1 P = 1
O = 4 O = 4
Na = 3 Na = 3
Br = 3 Br = 3
Type of chemical reaction:
The given reaction is double displacement reaction on which cation and anion of both reactants are replace with each other.
LRT benefits
The Costs and Benefits of Light Rail:
- reducing traffic congestion
- reducing pollution
- increasing property values
- fostering economic development
providing a means of transportation for the poor.
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