How many potassium atoms are in 250.0 grams of potassium? 1.66 x 10^−24 atoms k 3.85 x 10^24 atoms k 1.51 x 10^26 atoms k 5.88 x 10^27 atoms k

Hi!

The correct option would be 3.85x10^(24)

To find the number of atoms in 250g of potassium, we need to first calculate the number of atoms in

1 mole of Potassium = 39g which contains 6.022x10^(23) atoms of K

(Avogadro's constant value for the amount of molecules/atoms in one mole of any substance)

Solution

So as 39g of Potassium contains 6.022x10^(23) K atoms

1g of Potassium would contain 6.022x10^(23) / 39 = 1.544 x10^(22) atoms

So 250g of Potassium would contain 1.544x10^(22) x 250 = 3.86x10^(24) atoms

"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"