1) Answer: A hot pack feels warm when chemicals in it combine.
Explanation: Reactions or process in which heat is released(produced) are known as exothermic reactions or process and those in which the heat is absorbed are known as endothermic reactions or process.
If a beaker feels cools when chemical in it react then it means the chemicals have absorbed the heat energy from its surroundings and so it is an example of an endothermic process.
A hot pack feels warm when chemicals in it combine means the energy is released in the chemical reaction and so it is an example of an exothermic process.
Plants use the sun's energy for photosynthesis which is a process of forming food for the plants. Energy acts as a reactant in this process and so it is an example of endothermic process.
Frying an egg by heating it on a stove is an example of an endothermic process as the heat is required to fry the egg.
So, the only exothermic process is the second one, "A hot pack feels warm when chemicals in it combine."
2) In the given equation, heat is written as a product means the heat is released in the equation and so it is an example of an exothermic reaction.
So, the correct choice is the last one " It is exothermic because energy is released."
Answer: D is right
Explanation: One mole contains 6.0225 ·10^23 molecules
Despite of the substance
Answer: AIP
There are two types of substances mixture and pure substance. Mixture has NO chemical formula and a pure substance has a chemical formula. There are two types of pure substances, elements (mono atomic and molecular) and compounds ( covalent and ionic).
Ionic compounds do not exist in independent molecular form. They form three dimensional crystal lattice, in which each ion is surrounded by oppositely charged ion. so the ratio of ion is called the formula unit
Shred red cabbage ~ (3/4 of a very small head)
Put the cabbage pieces in a small container ~ ( you can use a Pyrex-4-cup measure, a bowl or even a plastic zipper bag)
Cover the cabbage with very hot water. Let it sleep until the water has cooled. (somewhere between lukewarm and room-temperature)
The purple liquid you've made is your indicator.
Pour it into a container and compost the cabbage.
Now look for substances that may be acids or bases.
Liquids are good, like fruits.
You can also use solids around for baking are good too. (such as baking soda, salt, sugar, cream of tartar...)
Get containers for mixing (such as tea cups, because they are small, shallow and white inside)
Pour the indicator into the tea cups and add an acid or base.
Lemon juice, rice wine vinegar, and apple cider vinegar, turn the cabbage-water indicator into a pink.
Orange juice or fresh oranges (same thing) turn the cabbage-water indicator into an orangish-pinkish color.
Baking soda turns the cabbage-water indicator blue.
Milk (non-fat) turns the cabbage-water indicator turn opaque and milky, yet purple.
An egg white (which won't get into the solution immediately until after a lot of stirring) turns the cabbage-water indicator blue.
Hint:
Bases mostly turn the indicator towards blue-ish colors such as purple, light blue, dark blue, opaque blue...
Acids mostly turn the indicator towards pink-ish colours such as orange-ish pink, floral pink...
(You'll have to keep on testing the cabbage-water indicator in after a day or two to see if the indicator quality persists or degrades.
