Experiment 2 - Introduction; Order of Reaction + Reaction of Sodium thiosulfate and Hydrochloric acid

A + B → C + D

The given hypothetical reaction.

Reactants A or B

Measuring rate of reaction; Observe the rate of disappearance in _____.

Products C or D

Measuring rate of reaction; Observe the rate of appearance of _____.

Rate of disappearance of A

−Δ[A]/Δt

Rate of appearance of C

Δ[C]/Δt

The rate of reaction depends on the _____ of one or more of the _____.

concentration, reactants

Formula for Rate of Reaction

Rate = k [A]^x [B]^y

[A] = ?

[B] = ?

molar concentration of A

molar concentration of B

^x and ^y = ?

powers to which the respective conc. must be raised to

k = ?

rate constant

First-order reaction (in B)

rate dependent and proportional to reactant concentration. Doubles the concentration of B, constant A = doubles the RoR

Second-order reaction (in A)

rate depends on the square of one/two reactants. Doubles concentration of A, constant B = increases RoR by a factor of 4

Third-order reaction

sum of all exponents.

concentration, temperature.

Rate constant; K; independent of the _____, varies with _____.

Sodium thiosulfate and Hydrochloric acid reaction

2HCl_(aq) + Na₂S₂O_3(aq) → 2NaCl_(aq) + SO_2(aq) + S_(s)↓ + H₂O

Goal

To measure the rate of reaction between sodium thiosulfate and hydrochloric acid

sulfur gradually forms a _____. making the solution _____ and mask a cross marked on paper.

precipitate, cloudy

1. Temperature

2. Concentration

3. Volume

the rate of reaction depends on;

measuring rate of reaction; how long it takes for the solution to become _____. (precipitation of _____)

cloudy, sulfur

measuring rate of reaction; RoR is _____ with the _____ of the time taken for a _____ of precipitation of _____.

directly proportional, inverse, sulfur

Objectives

To observe the effect of concentration and temperature upon the rate of the reaction of sodium thiosulfate and hydrochloric acid.

Safety Precautions

1. Wear your eye protection.

2. Do not inhale any fumes.

3. Sulfur dioxide is toxic and corrosive. Dispose of the solution immediately after the experiment following your teacher’s instructions.

4. Wash your hands when finished.