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Mnenie [13.5K]
3 years ago
9

Half life in chemistry I wasn't here when we did this

Chemistry
1 answer:
tatuchka [14]3 years ago
6 0
A half-life is the amount of time it takes for half of a substance to decay.

1.) After one half-life - 13.5mg.
After two - 6.75mg
Three - 3.375mg

2.) 250mg of Iron-59 will remain.

3.) 14 days is the half-life of Phospherous-32.
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In an aqueous solution, 42% of a substance dissociates to release hydronium ions. Which of the following statements is true for
const2013 [10]

Answer: The statement it is a weak acid is true for the substance.

Explanation:

An acid that dissociates completely when dissolved in water to give hydrogen (H^{+}) or hydronium (H_{3}O^{+}) ions is called a strong acid.

For example, HCl is a strong acid.

HCl + H_{2}O \rightarrow H_{3}O^{+} + Cl^{-}

An acid that dissociates partially or weakly when dissolved in water to given hydrogen or hydronium ions is called a weak acid.

For example, CH_{3}COOH is a weak acid.

CH_{3}COOH \rightleftharpoons CH_{3}COO^{-} + H_{3}O^{+}

A strong base is a base which when dissolved in water then it dissociates completely to give hydroxide ions.

For example, NaOH is a strong acid.

A weak base is a base which when dissolved in water then it dissociates partially or weakly to give hydroxide ions.

For example, NH_{3} is a weak base.

Hence, in an aqueous solution where 42% of a substance dissociates to release hydronium ions shows that the dissociation is less than 50%. This means that substance is dissociating weakly so, it is a weak acid.

Thus, we can conclude that the statement it is a weak acid is true for the substance.

5 0
3 years ago
Balance the following equation;C<img src="https://tex.z-dn.net/?f=C5H12%28g%29%2BO2%28g%29%3DC02%28g%29%2BH2O%28l%29" id="TexFor
Bumek [7]

put 8 in front of the oxygen in the reactants side to make it 16 molecules then put a 5 in front of the co2 in the product side to balance the carbon atoms then put a 6 in front of the H20 on the product side this balances both the hydrogen and oxygen atoms here is a representation

C5H12(g)+8O2(g)=5CO2(g)+6H20

4 0
2 years ago
6. 100 ml of gaseous hydrocarbon consumes 300
mario62 [17]

Answer:

  • <u><em>a. C₂H₄</em></u>

Explanation:

At constant pressure and temperature, the mole ratio of the gases is equal to their volume ratio (a consequence of Avogadro's law).

Hence, the <em>complete combustion reaction</em> that has a ratio of 100 ml of gaseous hydrocarbon to 300 ml of oxygen, is that whose mole ratio is 1 mol hydrocarbon : 3 mol of oxygen.

Then, you must write the balanced chemical equations for the complete combustion of the four hydrocarbons in the list of choices, and conclude which has such mole ratio (1 mol hydrocarbon : 3 mol oxygen).

A complete combustion reaction of a hydrocarbon is the reaction with oxygen that produces CO₂ and H₂O, along with the release of heat and light.

<u>a. C₂H₄:</u>

  • C₂H₄ (g) + 3O₂ (g) → 2CO₂(g)  + 2H₂O (g)

Precisely, for this reaction the mole ratio is 1 mol C₂H₄: 2 mol O₂, hence, this is the right choice.

The following analysis just shows that the other options are not right.

<u>b. C₂H₂:</u>

  • 2C₂H₂ (g) + 5O₂ (g) → 4CO₂(g)  + 2H₂O (g)

The mole ratio for this reaction is 2 mol C₂H₂ :5 mol O₂.

<u>с. С₃Н₈</u>

  • C₃H₈ (g) + 5O₂ (g) → 3CO₂(g)  + 4H₂O (g)

The mole ratio is 1 mol C₃H₈ : 5 mol O₂

<u>d. C₂H₆</u>

  • 2C₂H₆ (g) +7 O₂ (g) → 4CO₂(g)  + 6H₂O (g)

The mole ratio is 2 mol C₂H₆ : 7 mol O₂

7 0
3 years ago
Mr Singh is cooking using wo pans of oiling water. Both pans are made of steel, but one pan has a much thicker base than the oth
Sholpan [36]

Answer:

See explanation

Explanation:

When either pan is heated, energy is transferred via conduction. Conduction is the process by which heat is transferred through a material, the average position of the particles remaining the same.

When the pans are heated, the particles in each pan vibrate faster and transfer this energy rapidly to neighboring particles.

The pan with a thicker base has more particles in it than the pan with lighter weight base. Note that, The rate of heat transfer is inversely proportional to the thickness of the material in question. Hence, the thicker the base, the more the number of particles present and the longer the time it takes for the food to cook.

6 0
3 years ago
Help plss
Free_Kalibri [48]
Tertiary consumers are the highest trophic levels. 
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3 years ago
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