Answer: using a gas syringe to measure the gas produced, or calculating the reduction in the mass of the reaction solution.
Step-by-step explanation:
Reaction rate is calculated using the formula rate = Δ[C]/Δt, where Δ[C] is the change in product concentration during time period Δt. The rate of reaction can be observed by watching the disappearance of a reactant or the appearance of a product over time.