14 The concentration of urea (Mw-600 g/mol] in a solution prepared by dissolving

Question

14 The concentration of urea (Mw-600 g/mol] in a solution prepared by dissolving 16 g of urea in 39 A) 96 8) 68 C) 0.68 0163 0.11 15. The rate law for a reaction is Which one of the following statements is false? A) The reaction is first order in A B) The reaction is second order in B. C) The reaction is second order overal D) k is the reaction rate constant -7 E) 8] is doubled, the reaction rate will increase by a factor of 4. 16. As the temperature of a reaction is increased, the rate of the reaction increases because the A) reactant molecules collide less frequently 8) reactant molecules collide more frequently and with greater energy per collision C) activation energy is lowered D) reactant molecules collide less frequently and with greater energy per collision E) reactant molecules collide more frequently with less energy per collision 17. Which substance in the reaction below either appears or disappears the fastest? 4NH3 702 4NO2 + 6H2O A) NH3 B) o2 C) NO2 D) H20 E) The rates of appearance/disappearance are the same for all of these. 18. Which one of the following will change the value of an equilibrium constant? A) changing temperature B) adding other substances that do not react with any of the species involved in the equilibrium C) varying the initial concentrations of reactants D) varying the initial concentrations of products E) changing the volume of the reaction vessel

Explanation / Answer

Answer:

14) Given weight of urea=16 g, molecular weight of urea=60 g/mol and weight of water=39g.

We know that molality m=(weight/molecular weight)(1000/weight of water)

m=(16g/60g/mol)(1000/39)

m=6.837 mol/Kg=6.837 m.=6.8 m.

option B is correct.

15) Given rate law rate=k[A][B]^2

It states that

=> The reaction is first order with respect to A.

=> The reaction is second order with respect to B.

=> The overall order is 3.

=> k is called rate constant.

=> If [B] is doubled, then rate=k[A][2B]^2=4k[A][B]^2, rate increases by four times.

So option C is false.

As per guidelines I have to answer first question but I answered two questions for you.So please rate the answer.

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