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Leokris [45]
2 years ago
15

Americium-242 has a half-life of 6 hours. If you started with 24 g and you now have 3 g, how much time

Chemistry
1 answer:
kogti [31]2 years ago
7 0
How many times has it halved?

24/2 = 12
12/2 = 6
6/2 = 3

It halved three times.
It halves once every 6 hours.

18 hours have passed.
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What is the concentration of a solution made with 0.150 moles of KOH in 400.0 mL of solution?
otez555 [7]

Answer:

concentration = \frac{0.15}{0.4}=0.375 mol/L

Explanation:

Concentration: i is defined as the mole per litre.

concentration = \frac{mole}{volume in L}

mole=0.15

volume=400 ml=0.4 litre

concentration = \frac{0.15}{0.4}=0.375 mol/L

6 0
2 years ago
Which of the following shows an accurate combustion reaction?
Jet001 [13]

Answer:

  • <em>Cu + O₂  → CuO₂</em>

Explanation:

A <em>combustion reaction</em> is the reaction with oxygen along with the release of energy in form of heat or light.

Organic compounds (like CH₄) undergo combustion forming water and CO₂.

The combustion reaction of CH₄ is:

  • CH₄ + 2O₂ → CO₂ + 2H₂O

Hence, the first equation from the choices is not showing the combustion reaction of CH₄.

Not only organic compounds can undergo combustion. Metals and no metals can undergo combustion, i.e. metals and no metals can react with oxygen releasing light or heat.

The reaction of copper and oxygen (second choice) is a combustion reaction:

  • <em>Cu + O₂ → CuO₂</em>

The formation of water (2H₂ + O₂ → 2H₂O) is other example of a combustion reaction where no organic compounds are involved.

On the other hand, the other two equations from the choice list are not reactions with oxygen, so they do not show combustion reactions.

5 0
2 years ago
Find the molarity of 186.55 g of sugar (C12H22O11) in 250. mL of water.
Anna [14]

Answer:

The molarity of this sugar solution in water is 2.18 M

Explanation:

Step 1: Data given

Mass of sugar (C12H22O11) = 186.55 grams

Molar mass of C12H22O11 = 342.3 g/mol

Volume of water = 250.0 mL = 0.250 L

Step 2: Calculate moles sugar

Moles sugar = mass sugar / molar mass sugar

Moles sugar = 186.55 grams / 342.3 g/mol

Moles sugar = 0.545 moles

Step 3: Calculate molarity of the sugar solution

Molarity = moles sugar / volume of water

Molarity = 0.545 moles / 0.250 L

Molarity = 2.18 MThe molarity of this sugar solution in water is 2.18 M

6 0
2 years ago
his is the chemical formula for chromium(III) nitrate: . Calculate the mass percent of oxygen in chromium(III) nitrate. Round yo
Alinara [238K]

Answer:

\%\ Composition\ of\ iron=69.92\ \%

Explanation:

Percent composition is percentage by the mass of element present in the compound.

The formula for chromium(III) nitrate is Cr(NO_3)_3

Molar mass of chromium(III) nitrate = 238.011 g/mol

1 mole of chromium(III) nitrate contains 9 moles of oxygen

Molar mass of oxygen = 16 g/mol

So, Mass= Molar mass*Moles = 16*9 g = 144 g

\%\ Composition\ of\ iron=\frac{Mass_{iron}}{Total\ mass}\times 100

\%\ Composition\ of\ iron=\frac{144}{238.011}\times 100

\%\ Composition\ of\ iron=69.92\ \%

5 0
2 years ago
Chloe wants to lighten the color of her dark hair, which will require the use of both haircolor and hydrogen peroxide. hydrogen
bearhunter [10]

The answer is developer .

Chloe wants to lighten the color of her dark hair, which will require the use of both hair color and hydrogen peroxide.

Hydrogen peroxide (H₂O₂) is an example of a most commonly used developer in hair color.

Hydrogen peroxide lighten hair color, as it can dissolve darker pigment. According to the  natural hair color and the length of time a person will leave hydrogen peroxide on  hair,  hair can turn somewhere on the color spectrum between caramel, orange and yellow.





7 0
2 years ago
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