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The amount ofcalcium present in milk can be determined by adding oxalate to asample and measuring the massof calcium oxalate pre

Sauron [17]

Answer: The mass percent of calcium in milk is 0.107 %

Explanation:

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

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

Given mass of calcium oxalate = 0.429 g

Molar mass of calcium oxalate = 128.1 g/mol

Putting values in equation 1, we get:

$\text{Moles of calcium oxalate}=\frac{0.429g}{128.1g/mol}=0.0033mol$

The given chemical equation follows:

$Na_2C_2O_4(aq.)+Ca^{2+}(aq.)\rightarrow CaC_2O_4(s)+2Na^+(aq.)$

Sodium oxalate is present in excess. So, it is considered as an excess reagent. And, calcium ion is a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of calcium oxalate is produced from 1 mole of calcium ion

So, 0.0033 moles of calcium oxalate is produced from = $\frac{1}{1}\times 0.0033=0.0033mol$ of calcium ions

Now, calculating the mass of calcium ions by using equation 1, we get:

Moles of calcium ions = 0.0033 moles

Molar mass of calcium ions = 40 g/mol

Putting values in equation 1, we get:

$0.0033mol=\frac{\text{Mass of calcium ions}}{40g/mol}\\\\\text{Mass of calcium ions}=(0.0033mol\times 40g/mol)=0.132g$

To calculate the mass percentage of calcium ions in milk, we use the equation:

$\text{Mass percent of calcium ions}=\frac{\text{Mass of calcium ions}}{\text{Mass of milk}}\times 100$

Mass of milk = 125 g

Mass of calcium ions = 0.132 g

Putting values in above equation, we get:

$\text{Mass percent of calcium ions}=\frac{0.132g}{125g}\times 100=0.107\%$

Hence, the mass percent of calcium in milk is 0.107 %

7 0

3 years ago

Which statement best describes a solution?

lara31 [8.8K]

A mixture having a uniform composition where the components can't be seen separately and all components are in the same state best describes a solution.

In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent.

The correct answer between all the choices given is the third choice or letter C. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.

6 0

4 years ago

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The element carbon exists in several different forms. Pure carbon can be found in the form of diamonds, coal, and the graphite i

UNO [17]

Answer:

B) All carbon atoms have 6 neutrons.

Explanation:

The false statement from the given choices is that all carbon atoms have 6 neutrons.

There is a phenomenon called isotopy in chemistry.

Isotopy is the existence of two or more atoms of the same element having the same atomic number but different mass numbers due to the differences in the number of neutrons in their various nuclei.

These atoms of elements are called isotopes.
Carbon atoms generally have proton number of 6 which is the same as the atomic number.
As with all atoms, the mass number or atomic mass equals the number of protons and neutrons.

For the isotopes of carbon, their number of neutrons differs.

For example:

¹²₆C ¹³₆C ¹⁴₆C

The number of neutrons differs in the above isotopes.

Number of neutrons = mass number - atomic number;

¹²₆C , number of neutrons = 12 - 6 = 6

¹³₆C, number of neutrons = 13 - 6 = 7

¹⁴₆C, number of neutrons = 14 - 6 = 8

Therefore, based on the concept of isotopy, all carbon atoms do not have 6 neutrons.

7 0

3 years ago

Which is a property of barium (Ba)?

777dan777 [17]

Answer:

i think but i am not sure but according to me it mainly reacts yo non metals and i think its very reactive if my answer is wrong then comment below this question i will see it and i will get an opportunity to learn something new

4 0

3 years ago

128.3 grams of methane (CH4) is equal to how many moles of methane

Neko [114]

About 8.0 moles of methane.Number of moles = MassMolar mass.

And thus we get the quotient:

128.3⋅g16.04⋅g⋅mol−1=8.0⋅moles of methane.

Note that the expression is dimensionally consistent, we wanted an answer in moles, and the quotients gives, 1mol−1=11mol=mol as required.

6 0

3 years ago

Read 2 more answers