[erau86]

How do you calculate the mass of Carbon present in 380mL of 0.42 M K2CO3 (aq)?

I know that the SOE(STATEMENT OF  EQUIVALENT) is 1 mole of K=1 mole of C= 3 mole of O

[Hunter2]

1 mol K₂CO₃ is equivalent to 1 mole CO₂.

Calculate how many moles 380 ml of 0,42 M solution is.  With the molar weight of CO₂ you can calculate the mass.