Question

In the laboratory, you measure out 6.25 grams of sodium chloride (NaCl). How many moles of sodium chloride were present

Answer 1

0.107 mol moles of NaCl were present.

Step-by-step explanation:

To convert this mass into grams you need to use the formula:

moles= mass/molar mass

We have the mass but we do not have the molecular mass. To find the molar mass we should use the periodic table. In the periodic table, the atomic mass of Na is 23 and Cl is 35.5. To find the molar mass we have to multiply the moles by the atomic mass of all elements present and add it to the number of molecules.

1×( 23+35.5) (there is only one mole of the substance)

Molecular mass= 58.5 g/mol

Now going back to the original equation:

moles= 6.25 g/ 58.5 g/mol

moles= 0.106837606= 0.107 mol

Answer 2

I got 0.107mol (3sf)

Step-by-step explanation:

First, we'll have to find out the molar mass (Mr) of NaCl because this Mr is needed for another formula later on!

To calculate Mr of NaCl;

(23 × 1) + (35.5 × 1)

= 58.5

∴ Mr of NaCl = 58.5

Now, we can finally calculate the no. of mol with the formula;

no. of mol = mass/molar mass

Substitute the values like so;

no. of mol = 6.25/58.5

∴ no. of mol of NaCl = 0.107mol (3sf)

I hope this helps! Let me know if I miscalculated anything! :)