Learn about heat energy, how it moves, what its units are and how its calculated in this video!
energy is one of those things in science that can be hard to wrap your head around. Energy is the capacity to do work, or make something happen. It’s different from matter because it has no mass and takes up no space. You can really only detect it by it’s effect.
thermochemistry is the branch of chemistry that studies energy changes that occur during chemical reactions or changes of state.
There are two main categories for the different forms of energy, potential energy and Kinetic energy. Potential energy describes a situation where work isn’t currently being done, but it could be done under the right situation. chemical energy is the energy stored in the bonds of atoms. The kinds of atoms and their arrangements will determine how much energy is stored. Kinetic energy is the form with action. thermal energy is the internal energy of a substance which we can’t actually measure, but we can calculate energy when the thermal energy moves.potential energy is stored in the bonds of this chemical, isooctane, also known as gasoline. When the bonds break, an explosion occurs which turns the stored chemical energy into kinetic energy in the forms of movement and heat. The explosion moves the pistons and thereby the car, and the heat makes the engine hot. Heat is energy that transfers from one object to another because of a temperature difference between them. heat is the letter q.
heat always flows from a warmer object to a colder object. In the case of a cup of water with ice, the water is warmer than the ice, so heat will flow from the water to the ice, which will begin to melt the ice.When we talk about heat, we have to specify two things, our system or item that we’re focusing on, and the surrounds with a defined limit. This cat is giving of heat which goes from the system, to the surroundings. The cat is giving away it’s heat so we say that the q is negative. the q of the surroundings is absorbing the heat that the cat is releasing, so it stays positive. The amount of heat released by the cat will be equal to the amount of heat absorbed by the surroundings, which is according to the law of conservation of energy.Now the heat lost or gained could be the other way around. the surroundings give off heat. An ice cube is starting to melt. The ice cube is the system, the surrounding would include the air and the surface that the ice cube is on. Heat is leaving the surroundings and moving into the ice cube which causes it to melt. Notice it’s not the cold that moves, it’s always heat that moves. the cat releases heat into the surroundings so this is exothermic, which literally translates to “out-heat” the ice cube, however, absorbs heat from the surroundings so this is endothermic which means “in heat” endothermic systems have a positive q and exothermic have a negative q. Heat and temperature are not actually the same thing. Heat is the transfer of thermal energy, whereas temperature is the average kinetic energy of a sample of particles. You can’t directly measure heat. It’s just too complicated to calculate every possible source of heat energy in an object.We can measure temperature with thermometers. The main unit of measurement for heat is J and for temperature is celsius or kelvin. They only thing they have in common is that you can use temperature as part of a calculation to find heat. Heat is measured in J or calories. 1 J is the amount of energy to raise 1 gram of water 0.2390 o celsius, but in food science we use calories to measure energy. 4.184 J makes up one calorie with a lowercase letter c. to raise 1 gram of water 1 whole degree celsius it takes 4.184 Joules. The calorie is based on this information. Be careful when you read food labels, because you’re actually reading the kilocalorie which is written with a capital C. every object can be heated up. the amount of heat needed to increase the temperature of an object exactly 1 o celsius is called heat capacity. different object will have different heat capacities based on their mass and chemical composition. To account for mass we use specific heat capacity. this is the amount of heat it takes to raise the temperature of 1 g of the substance 1 o celsius. specific heat capacity is written as letter C and has units of J per g C.
Water has a very high capacity compared to metals like iron. This means that it will require more heat to raise the temperature of water than it does to raise the temperature of iron. ever boiled water in an iron pot? Even though the pot will be too hot to touch, the water may only be lukewarm.11.7 g of aluminum increases temperature from 12.0C to 24.5C with the addition of 132 J of heat. What is its specific heat? specific heat is equal to c=q/mt, so we plug in our data, making sure to subtract the initial temperature from the final temperature and we get 0.90 J/gC