7a: Measuring rate of reaction using a continuous monitoring method Flashcards
What are we measuring in this experiment
We are measuring the volume of carbon dioxide gas produced over a set time
what is the equation for this practical
2HCl(aq)+ CaCO3(s) = CaCl2(aq) + CO2(g) + H2O(l)
What are we trying to determine / find out in this practical
we are trying to find out the order with respect to hydrochloric acid
why does the rate not depend on the concentration of calcium carbonate/ CaCO3 chips
because it is a solid, to minimize surface area (SA) being an effect on the rate, large marble chips are used
why do we need to choose a specific quantity [volume and concentration] of HCl
Because the gas syringe measures a maximum volume of 100 cm³
How do we plot the graph for this reaction
Vfinal- Vt against t
Y axis: Vfinal - Vt
X axis: time (seconds)
How often do we measure the volume of carbon dioxide in the syringe during the experiment
Every 10 seconds.
what effectively is Vfinal - Vt
concentration of HCl. As a concentration of hydrochloric acid decreases over time
What is the procedure for this practical
1: Place about 10 g of marble chips in the test tube and add hydrochloric acid
2: put the acid in the test tube and allow a few seconds for the solution to become saturated with carbon dioxide. Put the stopper in place and start the timing.
3: Take a reading of volume at regular time intervals until the reaction is over and the volume no longer changes record your results in a results table.
why is the concentration of hydrochloric acid proportional to Vfinal - V
Because the rate of formation of carbon dioxide is inversely proportional to the rate of decrease in concentration of HCl.
How do you determine the order with respect to hydrochloric acid
after plotting the graph of time against Vfinal - Vt
you take gradients at certain volumes along the y axis.
then you plot a second graph with the rate (centimeters cubed seconds to the minus one)(cm3s-1) on the Y axis and the volume of CO2/ concentration of HCl on the x axis. a straight line indicates first order
