7. A number of reactions that take place on the surfaces of catalysts are zero order in the reactant. One example is the decomposition of ammonia on hot tungsten. In one experiment, the partial pressure of ammonia decreased from 21 kPa to 10 kPa in 770 s. (a) What is the rate constant for the zero-order reaction

14.29 Pa/s

Explanation:

Given that, for a zero order reaction;

[A] = [A]o - kt

[A] = pressure at time =t

[A]o = initial pressure

k = rate constant

t = time taken

10 * 10^3 Pa  = 21 * 10^3 Pa - 770k

10 * 10^3 Pa - 21 * 10^3 Pa = -770k

-11* 10^3 = -770k

k = -11* 10^3/-770

k = 14.29 Pa/s

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g

level 4 to level 2 : ))