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Shkiper50 [21]
4 years ago
5

99% of matter that makes up living organisms consists of how many elements?

Chemistry
1 answer:
DiKsa [7]4 years ago
6 0

Answer:

h2o or air

Explanation:

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Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid-fuel ro
melamori03 [73]

<u>Answer:</u> The mass of nickel (II) oxide and aluminium that must be used is 18.8 g and 4.54 g respectively.

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}      .....(1)

  • <u>For nickel:</u>

Given mass of nickel = 14.8 g

Molar mass of nickel = 58.7 g/mol

Putting values in equation 1, we get:

\text{Moles of nickel}=\frac{14.8g}{58.7g/mol}=0.252mol

For the given chemical reaction:

3NiO(s)+2Al(s)\rightarrow 3Ni(l)+Al_2O_3(s)

  • <u>For nickel (II) oxide:</u>

By Stoichiometry of the reaction:

3 moles of nickel are produced from 3 moles of nickel (II) oxide

So, 0.252 moles of nickel will be produced from \frac{3}{3}\times 0.252=0.252mol of nickel (II) oxide

Now, calculating the mass of nickel (II) oxide by using equation 1:

Molar mass of nickel (II) oxide = 74.7 g/mol

Moles of nickel (II) oxide = 0.252 moles

Putting values in equation 1, we get:

0.252mol=\frac{\text{Mass of nickel (II) oxide}}{74.7g/mol}\\\\\text{Mass of nickel (II) oxide}=(0.252mol\times 74.7g/mol)=18.8g

  • <u>For aluminium:</u>

By Stoichiometry of the reaction:

3 moles of nickel are produced from 2 moles of aluminium

So, 0.252 moles of nickel will be produced from \frac{2}{3}\times 0.252=0.168mol of aluminium

Now, calculating the mass of aluminium by using equation 1:

Molar mass of aluminium = 27 g/mol

Moles of aluminium = 0.168 moles

Putting values in equation 1, we get:

0.168mol=\frac{\text{Mass of aluminium}}{27g/mol}\\\\\text{Mass of aluminium}=(0.168mol\times 27g/mol)=4.54g

Hence, the mass of nickel (II) oxide and aluminium that must be used is 18.8 g and 4.54 g respectively.

4 0
3 years ago
Check my answer plz!! 100 points. Tell me if they are wrong! 1. You have three elements, A, B, and C, with the following electro
Artyom0805 [142]

look good w small changes below:

Answer:  


AB is an ionic compound. The electronegativity difference between A and B is greater.  


AC is an ionic compound. The electronegativity difference between A and C is greater.  


BC is a covalent compound because the electronegativity difference between C and B is small.


everything else look good!

6 0
3 years ago
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A solution of methanol and water has a mole fraction of water of 0.312 and a total vapor pressure of 21 torr at 39.9 degrees C.
Elan Coil [88]

Answer:

Explanation:

Given the details, we can say that

Pure methanol is a volatile solvent as the vapour pressure has a high value. This means that methanol - methanol intermolecular forces are weak in comparisson to water - water forces. When having about 30% of water in a methanol mixture, the mixture Pv decreased, showing that it is not a volatile mixture, so then there are strong intermolecular interactions between methanol - water, part of it due to the hydrogen bonds.

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Which of the following is a physical property? A. Flammability B. Heat of combustion C. Solubility D.Toxicity
Rasek [7]

I think it would be solubility but I’m not sure

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While the reaction in the lab text gives the product 4-methylcyclohexene, it is possible that several products are formed in thi
Contact [7]

Answer:

Explanation:

The step wise reaction mechanism for the formation of 1-methylcyclohexene is as follows.

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3 years ago
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