Understanding the Properties of Brass: A Comprehensive Overview

good morning in a moment we're going to take that warm metal at a temperature of around 64

degrees celsius and place it into the cold water at a temperature of 21.5 degrees celsius

and our goal will be to investigate what exactly is happening with this process notice of course

though that the temperature of the water is increasing so today we'll be determining the

specific heat capacity for zinc and brass so what exactly specific heat capacity well it's the amount of

energy in the form of heat required to raise the temperature of one kilogram of a substance by

one kelvin or one degree celsius as an example let's look at gold gold has a specific heat capacity of 129

joules per kilogram kelvin so imagine we had one kilogram of gold and imagine the initial temperature is

22 degrees celsius and that we want to raise the temperature to 23 degrees celsius

in other words we're increasing the temperature by one degree celsius or one kelvin well 129 joules per kilogram

kelvin means that if we want to increase the temperature

of a bar of gold that weighs 1 kilogram and we want to increase that temperature by 1 degree celsius

while we'll need 129 joules of heat energy of course if we want to increase that

temperature by 2 degrees celsius we'll need yeah can't hear you how much energy will

we need 258 joules of heat energy and so here's the formula for specific

heat capacity it's heat energy divided by the mass divided by the change in temperature

and these are the symbols we use to represent that formula c for specific heat capacity q for heat

energy m for mass and delta t for temperature change so ultimately we'll need to use that

formula for these two metals so we'll need to know the mass temperature change

and heat energy well here's the mass the zinc 70.1 grams and the brass 71.8 grams

so for this experiment we will initially warm some water then we'll place the two pieces of metal

inside the water the water's temperature is greater than 60 degrees celsius

next to that warm water we have two cups of water that are at room temperature

now what we'll be doing is we'll be transferring the warm metal into the cup of water

heat will flow from the warm metal to the water in the cup which is initially at room

temperature that flow of energy is represented by this equation this equation tells a story and the

story tells today is this that the energy gained by the water is coming from

the metal that's what that is saying we know that the water's temperature will begin to get warmer

but at the same time the metals temperature will get cooler now that formula assumes 100 percent

energy transfer it means that all of the energy from the metal will be transferred

to the water and nothing else now this is not possible because some of that energy may be transferred to the

air or it may be transferred to the surroundings

but today that's the assumption we're going to make and so in order to make this measurement we

also need to know the mass of the water i use the graduated cylinder 40 mils and the mass of water is 40 grams

and so we'll also have to measure the temperature change we'll measure the temperature change

with these probes the probes are circled in yellow they basically look like a small piece

of rice the reason why i've taken this photo is to show you that the probes even

though they're different they are measuring the same temperature so one of the probes we placed in the

warm water the whole point of that probe is to track the temperature of the metal which

is also in the warm water at this point it's reading 63.6 degrees celsius

the second probe will be placed in the cooler water the room temperature water now this is the table you'll need to

complete today notice i've already filled in the specific heat capacity for water

it's 4184 joules per kilogram degrees celsius it can also be written as 4184 joules

per kilogram kelvin to complete this table you'll need to fill in the mass

well if you didn't get those numbers previously please go back to the video and get those numbers now

so now i'm going to show you a video of the transfer taking place you should record the temperature of the

metal now notice i shake the excess water off also notice that i'm stirring the metal

around in the cup why am i doing that i'm doing that to distribute the heat

evenly now at this point it seems the temperature of the water is no longer

changing seems to have hit around 27.9 degrees celsius

and we say the metal and the water are in thermal equilibrium that means they have the same

temperature that will be the final temperature for this experiment

for brass and so from that video please record in your table

the initial temperature and the final temperature please also record the initial

temperature of the metal and also record the final temperature of the metal which is the same file

temperature as that of the water now these are the equations you'll need to complete the table

to get the temperature change its final temperature minus initial temperature this is for the water

and to get the heat energy of the water its mass times the specific heat capacity of the

water times the temperature change for the water

now this entire experiment hinges on this equation being correct it assumes that all of the energy all of

the heat energy lost by the metal will only be transferred to the water

is this a hundred percent valid no it's not but we're going to assume this anyways

we've tried to create an experiment to mimic that condition and so with that equation you know that

the heat energy for the metal is the same as the heat energy for the water except it's the negative of it

so the end game is to measure the specific heat capacity so i'll let you finish off this table

finally here is the experiment for zinc again i shake off the excess water and again i'm stirring the zinc around

to evenly distribute the heat everywhere in the water notice the temperature is rising

and eventually it'll plateau at that point we know that the zinc and the water have the same temperature the

same final temperature seems to be 27.3 degrees celsius and the water everywhere seems to be

that temperature so finally i'd like you to determine the percentage difference

for this experiment it's the experimental value for the specific heat capacity of the

metal minus the actual value for the specific heat capacity of the metal

divided by the actual value for the specific heat capacity of the metal so you will have to search the internet

for the specific heat capacity of brass or zinc these two bars mean absolute value meaning that whatever

number we get up here we automatically make it positive in addition i want you to discuss some

of the sources of error for this experiment i hope you have enjoyed this experiment

have a great day