Answer:
An example of engineering material, <em><u>are plastics,</u></em> they are derived from organic, natural materials, such as cellulose, coal, natural gas, salt and, of course, oil. Oil is a complex mixture of thousands of compounds and must be processed before being used.
Explanation:
Plastic production begins with distillation at a refinery, where crude oil is separated into groups of lighter components, called fractions. Each fraction is a mixture of hydrocarbon chains (chemical compounds formed by carbon and hydrogen) that differ in terms of the size and structure of their molecules. One of those fractions, naphtha, is the essential compound for the production of plastic.
Two main processes are used to make plastic: polymerization and polycondensation, and both require specific catalysts. In a polymerization reactor, monomers like ethylene and propylene join to form long polymer chains. Each polymer has its own properties, structure and dimensions depending on the type of basic monomer that has been used.
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:
The answer is
<h2>1.38 g/mL</h2>
Explanation:
The density of a substance can be found by using the formula
From the question
mass of liquid = 138 g
volume = 100 mL
The density of the liquid is
We have the final answer as
<h3>1.38 g/mL</h3>
Hope this helps you
Answer:
Explanation:
pH = − log [H+] , we can solve for [H+] as,
− pH = log [H+] ,
[H+] = 10^−pH,
so PH =2.4 in you case is
[H+] = 10^-2.4 =0.00398
The option are not correct it looks
Answer:
Electrons at the outermost energy level of an atom are called valence electrons. They determine many of the properties of an element. That's because these electrons are involved in chemical reactions with other atoms. Shared electrons bind atoms together to form chemical compounds.
Explanation:
