Is It Possible to Calculate the Mass of Zinc Added to a Stoppered Flask?

Is it possible to calculate how many grams of zinc was added to a stoppered flask containing excess HCl by measuring the change in pressure of the flask when all zinc has been reacted?

True / False

Answer:

True

It is possible to calculate how many grams of zinc was added to a stoppered flask containing excess HCl by measuring the change in pressure of the flask when all zinc has been reacted. This is because the change in pressure of the stoppered flask due to the reaction between zinc and excess HCl can be used to calculate the amount of zinc added.

When zinc reacts with HCl, it produces zinc chloride and hydrogen gas according to the balanced chemical equation: Zn + 2HCl -> ZnCl2 + H2. Since gases obey the ideal gas law (PV = nRT), the change in pressure can be related to the change in the number of moles of gas produced.

By measuring the pressure change and knowing the volume of the flask and the temperature, the number of moles of hydrogen gas can be determined, which corresponds to the number of moles of zinc reacted. With the molar mass of zinc, the mass of zinc added can be calculated.