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3 years ago

Explain why we use 1/12 in finding atomic mass unit ?

Chemistry

1 answer:

Nat2105 [25]3 years ago

7 0

Answer:

The u (amu is the old unit name) is 1/12 of the weight of an 12C atom. The way the u is chosen ensures that all core and atom masses are multiples of 1(±0.1) u.

Explanation:

Further explanation if needed...

Carbon 12 was chosen because the chemical atomic weights based on C12 are almost identical to the chemical atomic weights based on the natural mix of oxygen. Simply because the atomic mass is defined as 1/12 of the mass of 12C. Others isotopes of carbon (13C mostly, with an abundance of 1.1% approximately) account for an average atomic mass slightly above 12.

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3 years ago

Which of the models shown below best represents the modern understanding of the structure of the atom?

rjkz [21]

Answer:

The answer may be A because that's what I believe

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3 years ago

How many grams of MgCO3 are required to neutralize 200. mL of stomach acid HCl, which is equivalent to 0.0465 MHCl?

tester [92]

<h3>Answer:</h3>

0.392 g

<h3>Explanation:</h3>

We are given the following;

Volume of HCl is 200 mL

Molarity of HCl is 0.0465M

We are required to calculate the mass of MgCO₃ required

<h3>Step 1: Write the balanced equation for the reaction </h3>

The balanced equation for the reaction is;

MgCO₃(s) + 2HCl(aq) → MgCl₂(aq) + CO₂(g) + H₂O(l)

<h3>Step 2: Calculate the moles of HCl</h3>

When given the molarity of a compound and the volume, the number of moles can be calculated by;

Number of moles = Molarity × Volume

Therefore;

Volume of HCl = 0.0465 M × 0.2 L

= 0.0093 moles

<h3>Step 3: Calculating the number of moles of MgCO₃</h3>

From the equation, one mole of MgCO₃ reacts with two moles of HCl

Therefore, the mole ratio of MgCO₃ : HCl is 1 : 2

Hence, moles of MgCO₃ = Moles of HCl ÷ 2

= 0.0093 moles ÷ 2

= 0.00465 moles

To calculate the mass of a compound we need to multiply the molar mass of a compound with the number of moles.

Molar mass of MgCO₃ is 84.314 g/mol

Thus, Mass of MgCO₃ = 0.00465 moles × 84.314 g/mol

= 0.392 g

Therefore, 0.392 g of MgCO₃ are required to neutralize the acid.

3 0

4 years ago

If nicotine has a molar mass of 160±5g/mol , what is its molecular formula?

navik [9.2K]

Answer:

C10H14N2

Explanation:

I don't believe one can deduce the molecular formula from just it's molar mass. There are too many possible combinations of elements that could add to the same mass. This is the correct formula for nicotine, taken from known information, not from an analysis of the molar mass alone. One can confirm the molar mass is in the correct range:

C10: 10*12 = 120

H14: 14*1 = 14

N2: 2*14 = <u> 28</u>

Total = 162 which is 160±5g/mol

8 0

3 years ago

Ammonium phosphate is an important ingredient in many fertilizers. It can be made by reacting phosphoric acid with ammonia . Wha

Dmitry [639]

Answer:

7.5 g

Explanation:

There is some info missing. I think this is the original question.

<em>Ammonium phosphate ((NH₄)₃PO₄) is an important ingredient in many fertilizers. It can be made by reacting phosphoric acid (H₃PO₄) with ammonia (NH₃). What mass of ammonium phosphate is produced by the reaction of 4.9 g of phosphoric acid? Be sure your answer has the correct number of significant digits.</em>

<em />

Step 1: Write the balanced equation

H₃PO₄ + 3 NH₃ ⇒ (NH₄)₃PO₄

Step 2: Calculate the moles corresponding to 4.9 g of phosphoric acid

The molar mass of phosphoric acid is 98.00 g/mol.

$4.9 g \times \frac{1mol}{98.00g} = 0.050mol$

Step 3: Calculate the moles of ammonium phosphate produced from 0.050 moles of phosphoric acid

The molar ratio of H₃PO₄ to (NH₄)₃PO₄ is 1:1. The moles of (NH₄)₃PO₄ produced are 1/1 × 0.050 mol = 0.050 mol.

Step 4: Calculate the mass corresponding to 0.050 moles of ammonium phosphate

The molar mass of ammonium phosphate is 149.09 g/mol.

$0.050mol \times \frac{149.09 g}{mol} = 7.5 g$

6 0

3 years ago

Explain why we use 1/12 in finding atomic mass unit ?​

Explain why we use 1/12 in finding atomic mass unit ?