What is a chemical change

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Answer 1

Answer:

A chemical change Is any change that results in the formation of new chemical substances .

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Calculate the hydrogen-ion concentration [H+] for the aqueous solution in which [OH–] is 1 x 10–11 mol/L. Is this solution acidic, basic, or neutral? Show all work.

Answers

If we have $[H+][OH-]= Kw = 1.0 x 10^-14$
Then $[H+]= Kw/ [OH-]= 1.0x 10^-14$ $/ 1 x 10^-11 =1 x 10^-3 mol/L$
And here is the solution - as you can see it is an acidic one :
$pH = - log [H+]= - log 1 x 10^-3 = 3 \ \textless \ 7$

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A). Polonium is a rare element with 33 radioisotopes. The most common one, 210Po, has 82 protons and 128 neutrons. When 210Po decays, it emits an alpha particle, which is a helium nucleus (2 protons and 2 neutrons). 210Po decay is tricky to detect because alpha particles do not carry very much energy compared to other forms of radiation. They can be stopped by, for example, a sheet of paper or a few inches of air. That is one reason that authorities failed to discover toxic amounts of 210Po in the body of former KGB agent Alexander Litvinenko until after he died suddenly and mysteriously in 2006. What element does an atom of 210Po change into after it emits an alpha particle? b). Some undiluted acids aremore corrosive when they are diluted with water. That is why laboratory workers are told to wipe acid splashes with a towel before washing with a copious amounts of water. Explain.

Answers

Answer:

a) Lead

b) Below

Explanation:

a) ₂₁₀ Po⁸⁴ ⇒ α + ₂₀₈Pb⁸²

b) Acids are extremely corrosive substances, so they must be cleaned soon as possible because they can damage not only the furniture but also clothes and skin of the laboratory workers.

Before cleaning the polluted area with water, acids must be clean with towels in order to reduce the amount of acid.

The reaction between the acids and water are very explosive, they are exothermic reactions, that means that they increase the temperature of the area polluted and it can cause more damage. That's why the area must be cleaned with towel before add water.

The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. combustion of 3.61 mg of ethyl butyrate produces 8.22 mg of co2 and 3.35 mg of h2o. what is the empirical formula of the compound

Answers

Answer:

Empirical Formula = C₃H₆O₁

Solution:

Data Given:

Mass of Ethyl Butyrate = 3.61 mg = 0.00361 g

Mass of CO₂ = 8.22 mg = 0.00822 g

Mass of H₂O = 3.35 mg = 0.00335 g

Step 1: Calculate %age of Elements as;

%C = (mass of CO₂ ÷ Mass of sample) × (12 ÷ 44) × 100

%C = (0.00822 ÷ 0.00361) × (12 ÷ 44) × 100

%C = (2.277) × (12 ÷ 44) × 100

%C = 2.277 × 0.2727 × 100

%C = 62.09 %

%H = (mass of H₂O ÷ Mass of sample) × (2.02 ÷ 18.02) × 100

%H = (0.00335 ÷ 0.00361) × (2.02 ÷ 18.02) × 100

%H = (0.9279) × (2.02 ÷ 18.02) × 100

%H = 0.9279 × 0.1120 × 100

%H = 10.39 %

%O = 100% - (%C + %H)

%O = 100% - (62.09% + 10.39%)

%O = 100% - 72.48%

%O = 27.52 %

Step 2: Calculate Moles of each Element;

Moles of C = %C ÷ At.Mass of C

Moles of C = 62.09 ÷ 12.01

Moles of C = 5.169 mol

Moles of H = %H ÷ At.Mass of H

Moles of H = 10.39 ÷ 1.01

Moles of H = 10.287 mol

Moles of O = %O ÷ At.Mass of O

Moles of O = 27.52 ÷ 16.0

Moles of O = 1.720 mol

Step 3: Find out mole ratio and simplify it;

C H O

5.169 10.287 1.720

5.169/1.720 10.287/1.720 1.720/1.720

3.00 5.98 1

3 ≈ 6 1

Result:

Empirical Formula = C₃H₆O₁

What is made up of biotic and abiotic features

Answers

biotic - animals anything tht is living abiotic anything tht is non-living

Biotic-living organisms within an ecosystem.
Abiotic-non-living things.

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