A chemical reaction is studied in which the rate is given by the relation

PHYSICS · Subjective · A Level · Physics · Measurements and their errors · Measurements and their errors

Problem

A chemical reaction is studied in which the rate

R

is given by the relation

R = \dfrac{k\,V^{2}}{t}

, where

k

is a constant. In an experiment the following measured values were obtained:

k = 4.73\times10^{3}

(unitless, 3 significant figures),

V = 1.206\,\text{L}

and

t = 0.845\,\text{s}

. (i) Calculate

R

and state it in proper scientific notation with the correct number of significant figures. (ii) If

t

is later corrected to

0.842\,\text{s}

, determine the percentage change in the reported value of

R

, again observing the appropriate significant–figure rules at each stage. (iii) Briefly justify the rounding decisions you made in parts (i) and (ii).

Related theory

Precision & Reporting
Significant figures and magnitude
Significant figures and rounding

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