Brand new semester and kicking it off with a brand new idea for a chemistry take home lab. Ever wonder what the actual cost in dollars was for a single shower? Whether you are a high school student or a curious at home learner, it's time to get your thermochemistry off to a great start with an activity that helps to learn about specific heat capacity, practical skills about household technology, and a deeper understanding of the power and cost of taking a shower.
Everytime I'm trying to design a new activity I always try and think of something that can have a practical use. Don't get me wrong, sometimes theoretical problems for the sake of theoretical problems can be fun, but when it comes to labs I really enjoy having something pragmatic.
So here's the plan with this lab which you can find attached on the right. Have students measure the temperature of the water of a typical shower. Learn a few things such as knowing that the cup they collect the water in should doused in the water for a bit so that they aren't pouring warm water into a cold cup. Then they are going to collect a sample of shower water over a period of 5 seconds and use that volume to determine the total volume of a full shower length. Following that, they are going to have to locate the hot water heater and their house and do some estimates as they measure the room temperature of the room where it's stored. This should give us atleast a rough estimate of the temperature increase of the water. We'll be using the cost of power in Nova Scotia converting the cost per kWh into cost per Joule and from there we should be able to get a fairly decent estimate of the cost of a shower. Sure it's a shower assumed to be running at 100% efficiency but hey, it's a good bit of fun.
Objective # 1 - Need to be doing some practice with specific heat capacity and capacity of samples in general.
Objective # 2 - Time to practice some measuring skills. Taking repeated samples and averaging, recognizing outliers, and if necessary repeating the experiment. It's a quick little experiment. No reason to have data that is wildly all over creation.
Objective # 3 - Create a little independence. Students of mine and their parents can be pretty sure that I don't agree with sending home lots of work. I like studies to happen during the school day so that students are free to pursue their own interests once they leave. However, every once in a while I like to give a task that sets students loose to explore on their own. This is one of those situations.
Objective # 4 - Realistic Skills! I want teenagers to know what a hot water heater is, where it's located and how to adjust one. This time next year my grade 12s might be sitting in an apartment trying to figure out how to adjust one. Calculating the cost of a shower in actual dollars. For some, that can be pretty eye opening.
Objective # 5 - Going green. Hard to pass up an opportunity for a little talk about resource conservation.
So that's what I was working with. Developing a lab that can do all of these things. Now this isn't a lab activity that is going to take up an hour, but a lot of times activities like this aren't designed to be your daily lesson plan. They are supposed to be a learning experience for the students. Expect a good twenty minute talk as you outline the assignment and explain expectations and then expect another twenty minute talk as you bring it all together.
This is the beginning of what can be a very enriching activity. I will have my students take pictures of their procedures and create digital records of their lab work. What you do with this activity and how fulfilling you make it for your students is entirely up to you. Decide if you want them to just answer the calculations, or do you want them to write up a lab report. In the end though, hopefully your students get the opportunity to learn about specific heat capacity and develop some STSE skills at the same time.