Catalytic converters made of palladium (Pd) reduce automobile pollution by catalyzing the reaction between unburned hydrocarbons
and oxygen. How does Pd increase the rate of this reaction?
A: By cooling the reactants
B: By splitting the oxygen atoms
C: By giving the hydrocarbons a negative charge
D: By decreasing the activation energy
A: By cooling the reactants
B: By splitting the oxygen atoms
C: By giving the hydrocarbons a negative charge
D: By decreasing the activation energy
2 answers:
Answer: D: By decreasing the activation energy
Explanation: A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and convert to products.
Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.
The catalyst itself does not take part in the chemical reaction and is regenerated as such at the end.
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Answer:
1.327 g Ag₂CrO₄
Explanation:
The reaction that takes place is:
- 2AgNO₃(aq) + K₂CrO₄(aq) → Ag₂CrO₄(s) + 2KNO₃(aq)
First we need to <em>identify the limiting reactant</em>:
We have:
- 0.20 M * 50.0 mL = 10 mmol of AgNO₃
- 0.10 M * 40.0 mL = 4 mmol of K₂CrO₄
If 4 mmol of K₂CrO₄ were to react completely, it would require (4*2) 8 mmol of AgNO₃. There's more than 8 mmol of AgNO₃ so AgNO₃ is the excess reactant. <em><u>That makes K₂CrO₄ the limiting reactant</u></em>.
Now we <u>calculate the mass of Ag₂CrO₄ formed</u>, using the <em>limiting reactant</em>:
- 4 mmol K₂CrO₄ *
= 1326.92 mg Ag₂CrO₄
- 1326.92 mg / 1000 = 1.327 g Ag₂CrO₄