The molar mass-of H2O is 18.02 gram /mol. How many moles are present in 3.33 x 1024 molecules of H2O?
Select one:
a. 9.97 moles H20
b. 99.7 moles H2O
c. 2.00 x 1048 moles H20
d. 5.53 moles H20

Answer

5.53moles

Explanation:

Given parameters

Number of molecules = 3.33 x 10²⁴

Unknown

Number of moles = ?

Solution

A mole of a substance contains the Avogadro's number of particles.

1 mole of a substance = 6.02 x 10²³

So, 3.33 x 10²⁴ molecules will contain;

3.33 x 10²⁴ / 6.02 x 10²³

= 5.53moles

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"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"