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2 years ago

How many particles are in 2.5 mol of water, H2O?

Chemistry

2 answers:

scZoUnD [109]2 years ago

8 0

There are 1.5x1024 molecules

LUCKY_DIMON [66]2 years ago

3 0

Answer: 1.5×1024 molecules

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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]

<u>Answer:</u> The mass percent of calcium in milk is 0.107 %

<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)

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

What is enthalpy of atomisation

Komok [63]

The enthalpy of atomization (also atomisation in British spelling) is the enthalpy change that accompanies the total separation of all atoms in a chemical substance (either a chemical element or a chemical compound)

5 0

3 years ago

Which of the following describes the arrangement of valence electrons in a bond between H and F?

Sloan [31]

C; The Valence electrons spend more time around the atom of F

6 0

3 years ago

24.08 x 10^23 atoms of Boron (B) is equal to how many moles of Boron?

padilas [110]

1 mole ----------- 6.02 x 10²³ atoms
? mole ---------- 24.08 x 10²³ atoms

moles B = ( 24.08 x 10²³) x 1 / 6.02 x 10²³

moles B = 24.08 x 10²³ / 6.02 x 10²³

= 4 moles

Answer B

hope this helps!

5 0

3 years ago

Read 2 more answers

Are nails in a jar with water a chemical change

Digiron [165]

I would say it is a chemical change because after a while, the nails start to rust. Now they only rust after about a week though. But rust is a chemical change.

7 0

3 years ago