how many grams of CO2 are made when 35 mls of 2.14 molar HCl reacts with Na2CO3?

Balanced equation for the reaction:
2HCl + Na₂CO₃ → 2NaCl + H₂O + CO₂
Mole ratio: HCl : CO₂ = 2 : 1

No. of moles of HCl reacted = (2.14 mol/L) × (35/1000) = 0.0749 mol
No. of moles of CO₂ made = (0.0749 mol) × (1/2) = 0.03745 mol

Molar mass of CO₂ = (12.0 + 16.0×2) g/mol = 44.0 g/mol
Mass of CO₂ made = (0.03745 mol) × (44.0 g/mol) = 1.6 g (to 2 sig. fig.)

Grams of CO2....

Simply use the unit-factor method.... where you have a one-line setup, one chain calculation and almost zero chance of error.

Na2CO3(s) + 2HCl(aq) --> 2NaCl(aq) + CO2(g) + H2O(l)
...................... 35 mL .............................. ?g
...................... 2.14M

0.035L x (2.14 mol HCl / 1L) x (1 mol CO2 / 2 mol HCl) x (44.0g CO2 / 1 mol CO2) = 1.6g CO2

The answer can only be expressed to two significant digits since the volume is given to two significant digits.

2.14 molar means one liter of the solution contains 2.14 moles of hydrochloric acid. To determine the number of moles, multiply the volume in liters by the number of moles per liter.

n = 0.035 * 2.14 = 0.0749

The next step is to write the balanced equation for this reaction.
2 HCl + Na2CO3 → CO2 + H2O

According to the balanced equation above, two moles of hydrochloric acid reacts with one mole of sodium carbonate to produce one mole of carbon dioxide and one mole of water. This means the number of moles of carbon dioxide is one half of the number of moles of hydrochloric acid.

For CO2, n = ½ * 0.0749 = 0.03745
For CO2, mass of one mole = 12 + 2 * 16 = 44 grams
To determine the mass of carbon dioxide, multiply the mass of one mole by the number of moles.

Mass = 0.03745 * 44 = 1.6478 grams.

Rounded to two significant digits, the mass of carbon dioxide is 1.6 grams. I hope this is helpful for you.