Consider the following reaction:
Zn(s)+ 2HCl(aq)--> ZnCl2(aq)+ H2(g)
Which of the following instruments could be used to monitor the rate of the reaction in an open system?
I. Balance
II. Pressure Gauge
III. pH meter
A I, II and III.
B I and II only.
C I and III only.
D II and III only.
I do not understand why the answer is not A. Since the reaction produces a gas, would it therefore not be ideal to measure the pressure of the system with a pressure gauge? More gas = more pressure right?