What is the mass of Na2CO3 required to make a 500 mL standard solution of 0.400 mol/L Na2CO3?
a. 212 g
b. 23.4 g
c. 25.8 g
d. 27.39

21.2 g

Explanation:

Step 1: Given data

Step 2: Calculate the moles of Na₂CO₃ (solute) in the solution

We will use the definition of molarity.

C = moles of solute / liters of solution

moles of solute = C × liters of solution

moles of solute = 0.400 mol/L × 0.500 L = 0.200 mol

Step 3: Calculate the mass corresponding to 0.200 moles of Na₂CO₃

The molar mass of Na₂CO₃ is 105.99 g/mol.

0.200 mol × 105.99 g/mol = 21.2 g

3 hours because it is a decent distance.

"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"