How do convert Calories to Joules
How do you convert calories to Joules? A unit is an amount of a physical quantity. For example, one Joule is a certain amount of energy. One calorie that’s calorie with a lowercase C is another unit that indicates a different amount of energy. The amount of energy in one calorie is the same amount of energy in 4.184 joules. So we can write the equation as one calorie equals 4.184 joules. If you want to know how many calories are in 1520 tools, just multiply it by one calorie over 4.184 joules.
This will convert the units without changing the amount of energy. Because it just multiplies the value by one because one calorie of our 4.184 joules is equal to 1 because 1 calorie equals 4.184 joules. By doing the math we find that joules canceled. Because joules/joules are just 1 and we are left with 363 calories. Likewise, if you wanted to convert 880 calories to joules. Multiplied by the inverse of the ratio of 4.184 joules per calorie to get calories to cancel.
And we are left with three thousand six hundred and eighty joules. That’s how to convert units but don’t get calories mixed up with calories. That’s calories with a capital C. One calorie is actually equal to one-kilo calorie or one thousand calories with a lowercase C. So to convert 19600 joules to calories multiplied by 1 calorie / 4.184 joules to get four thousand six hundred eighty-five calories and divide by 1,000 to get four point six eight calories.
Joule and calorie conversions
Suppose Say that you took 25 you spent 25 joules doing the last problem. You want to convert that measurement into calories. So let’s take our 25 joules. We know that our equation is 4.184 joules equals one calorie. So we can simply put that into a conversion factor and say that joules on bottom 4.184 of them equal one calorie our joules cancel.
And we come out with five-point, nine- seven-five calories obviously that’s not significant digits. So we round up to two. We get six points zero calories. Now the opposite one if we wanted to go from calories to joules. Simply the opposite set say we had 12 calories would take our conversion factor input calories on the bottom jewels on the top 4.184 joules equals 1 calorie. We multiply that out calories cancel. We get fifty point two zero eight fuels which would equal 50 point tools and second indigents.
calories and joules
Today I’m not talking about measuring energy changes in this section. I’m gonna ask how is he measured well. There’s a couple of different things you need to know. There’s a couple of units that we use all very often. One is a calorie and calorie is the energy required to increase the temperature of one gram of water one degrees C. Joule is the energy required to apply a force of one Newton over a distance of one meter. And we abbreviate that with a capital J now that doesn’t make much sense to chemists. It makes more sense to the physicist Buttered unit of energy in the metric system. So for our purposes just consider that one calorie equals 4.184 joules of energy.
Now you may be familiar with another energy in food called the calorie strangely enough. However, this calorie has a capital C an uppercase C and it’s equal to a thousand little C calories. Or we sometimes call it 1 kcal and 1 kcal is really the convention in Europe for measuring energy in food. So we use the calories of Big C in Britain. They use calories to use kcals to represent galleries with a big C. Well if we have to convert back and forth between the two is actually pretty simple. If you remember, this one important number 4.184 joules per calorie.
So if we have 60 points one calories and want to convert that into joules. We then multiply by 4.184 joules per calorie because what that does is that makes these units here cancel. When you want to get rid of goes in the bottom, the one you want to keep goes on top. So our answer is going to be in joules or 250 one tool. We can also go back the other way.
We can convert 28.4 jewels into calories Simply by dividing so the one we want to get rid of always goes on the bottom. In this case, one gets rid of joules and come back with calories going keep has to be on top. So this J cancels this J gives us an answer in calories which is six point seven nine and that’s really all there is to it to go back and forth between calories and joules.
So let’s try an example let’s calculate the amount of energy required to raise 7.4 grams of water from 29 degrees C to 46 degrees C .And we want the answer in joules well. We know that 4.184 joules are required for regram degrees C.Therefore we multiply by seven-point for old grams that’s the total mass what that does that makes this gram cancel and then we multiply by the temperature change which here is 17 degrees C .And look this C cancels this C.One on top ones on the bottom got joules leftover we multiply four point one eight four by seven point four by 17.
And we get 526 joules of energy required. I’ve got a couple more here one is to calculate the amount of energy to raise the temperature of one liter of water from 25 degrees C to boiling which is at 100 degrees C do it invoke joules. And calories and just to give you a hint the answer is 3.14 kilojoules and 75 kilocalories. Therefore we try to figure that one out on your own using what you learned up here okay. Let’s see if not follow along with me and we’ll fix this up well. We start with 4.184 joules per gram degrees C.We have one liter of water here and one liter of water equals a thousand grams. So we have to then multiply by a thousand grams of water per liter.
And hey look gets this gram to cancel. Now we’ve got to figure out how many degrees it needs to go up well. We always subtract the final temperature from the initial temperature. So 100 degrees C minus 25 degrees C well we know that equals 75 degrees C.So we’ll just put that in here okay. Now we just multiply across 4.184 times, a thousand times seventy-five equals 314-kilo joules. Or you might have gotten three hundred and fourteen thousand joules which is the same as 314 kilojoules.
Now I change that into kilocalories. We take our 314-kilo joules and we then have 4.184 kilojoules per kilocalorie. And that gives us an answer of 75 KCAL oh well these caves really just cancel each other out it’s all one kilocalorie the same as 4.184 kilojoules.
So here you kind of stuck with that one you can try this one calculate the Joule of energy required to heat 454 grams of water from five-point four degrees C to 98.6 degrees C and the answer and I’ll do it in joules this time is one point seven times ten to the fifth joules so it’s gonna pause I’ll give you min to solve that and I’ll come back with the answer well we do this exactly the same way 4.184 joules per gram degree C well how much do we have.
454 grams of water oh that’s gonna make the grams cancel now we just gotta find a way to make the degrees C cancel so we then multiply by the difference in temperature so we subtract the first one from the second one so ninety-eight point six minus five point four degrees C we get that difference we multiply it all the way across we get one point seven times ten to the fifth.
Interconverting calories and Joules
Now I am going to talk about Interconverting calories and joules so the unit of energy that we use in science is called the Joule okay. So up here the Joule is the unit of energy used in chemistry problem is that there is another discipline that uses a different one. That often will be interchanged and that’s nutrition uses a calorie. Therefore calories in nutrition and it’s defined okay. It’s defined to be the amount of energy to convert one gram of water one degree Celsius. It’s still in the metric system somewhat it’s based in the metric system.
But calorie you’ll hear are calories in terms of like food calories are actually kilocalories. A kilocalorie is equal to a capital C calorie and it’s called a food calorie. So your candy bar has food calories on it calories and what we’re doing here is we’re converting between calories which is the amount of heat. It takes to raise a gram of water. And it’s essentially as a specific heat of like water.
How much energy does it take to raise water one gram or food calories which is kilocalories? And see this is all food so that’s why of Killah cars and joules or kilojoules probably being more useful because it’s this would be a lot of joules. I need a couple of definitions actually just one write it here. One calorie is defined so this is not significant figures defined to be 4.184 joules exactly. When 4.184 joules is one calorie so we’re going to use that as the conversion factor for all of this. We have three of these to do.
The first one is calories two kilocalories. Let’s start here. We’ve got two point two five times ten to the five calories. There are kilometers and there are ten to three calories in a kilocalorie. Therefore three of these will cancel with three of these leaving you two of these most of the time. Then you would simply just make it 225. You don’t have lots of scientific notation. If it’s just very small numbers so this is going to be 225 periods 18 and 25. Right now we need to go from kilocalories to kilojoules all right. So we have two hundred and kilojoules. Remember joules will go from calories and I’m going to go back here to two hundred 2.25 times ten to the fifth calories. And we’ll remember that in one calorie, there are exactly 4.184 joules calories will cancel.
Jewels but Kilojoules
Now I’m wanting not to go to jewels but kilojoules. So let’s just go ahead and do that there are 10 to the 3rd or 1000 jewels and kilojoules. As this is joules so jewels will cancel the answer will be in kilojoules. I want to point to five times four point one eight four divides it by 10 to the third alright. I’m going to have to round all of these are in three significant figures. I need to round that up somewhere around to three significant figures and I get 941 kilojoules. The second one I have 145 kilocalories and one kilocalorie.
There are a thousand calories that mean that this is 145 times a third. But I need it to be just one digit so this would be one you could put. This is a calculator he would tell you but the scientific notation is after one digit.
It’s one point four-five times 10 to the fifth calories. So now after this, I can just use this and keep going in one calorie. There are 4.184 joules calories will cancel and then there’s 10 to the third joules. Kilojoule joules now cancel all right. So I’ve got 145 times a thousand times 4.184 equals divided by a thousand. I’ve got six so six-point six-eight and I need three significant digits. This is gonna be 607 .
Kilojoules a corn muffin will give you a cup of cooked rice
That’s how many kilojoules a corn muffin will give you a cup of cooked rice. 941 I’d rather have the rice 3 ounces of cook sirloin steak. There you go it’s going to give you here’s and jewels. Now have to go backward. There’s the last one I’ve got one point zero times 10 to the third kilograms. I’ll kill ax so in one kilojoule there’s 10 to the third joules counter is it canceled. Now I’m in Jules. I remember that there are 4.184 joules in the calorie, okay Jules cancel. I’m now in calories and that’s where I want to be here so let’s do that 1 time 10 to the 3rd times a thousand equals / 4.184. I’m going to express that scientific notation. I want 3 significant figures.
So that’s going to be 2 point 3 9 times 10 to the 5th. I write that down 2.3 9 times 10 to the 5th and that’s in calories and in I get rid of calories and go to kilocalories. There are a thousand kilocalories so I could just take that number and divide by a thousand. And I’ve got 2.3 nine times 10 to the 2 most of the time you would not do that. It’s just too close 239 and the not a huge number you can write down 239. It’s just two digits past the two. I think that’s normally that’s what you would do normally 239. You only use scientific notation when it’s very very big or very little okay not bad not a terrible lesson today. I think you can do this it’s just a little bit of algebra even though how to scare you.