Chlorine dioxide, ClO2, has been used as a disinfectant in air conditioning systems. It reacts with water according to the following equation. ... HCl If 142.0 g of ClO2 is mixed with 33.0 g of H2O, how many grams of which reactant remain if the reaction is complete?

Write the equation. You didn't complete it.

ClO2 + H2O ==>

Then balance the equation.
Convert 33.0 g H2O and 142.0 g ClO2 to moles. moles = grams/molar mass.

Using the coefficients in the balanced equation, convert moles of each to moles of product. The reactant producing the smaller number of moles of the product will be the limiting reagent. That will identify the limiting reagent, which by the way, will be used completely.
To determine how much of the OTHER reagent remains:
a. Convert moles of the limiting reagent to moles of the OTHER reagent using the coefficients in the balanced equation. This will be the moles of the other reagent used. Subtract the initial moles from the moles used to determine moles remaining. Then convert that to grams. g = moles x molar mass.
Post your work if you get stuck.

To find out how many grams of each reactant remain after the reaction is complete, we need to calculate the limiting reactant. The limiting reactant is the one that is completely consumed in the reaction, determining the maximum amount of product that can be formed.

First, we need to determine the number of moles of ClO2 and H2O using their molar masses. The molar mass of ClO2 is 67.45 g/mol, and the molar mass of H2O is 18.02 g/mol.

Number of moles of ClO2 = mass of ClO2 / molar mass of ClO2
= 142.0 g / 67.45 g/mol
= 2.11 mol

Number of moles of H2O = mass of H2O / molar mass of H2O
= 33.0 g / 18.02 g/mol
= 1.83 mol

Next, we need to determine the stoichiometric ratios of the reactants in the balanced equation. From the given equation, we can see that the ratio of ClO2 to H2O is 2:1.

The stoichiometric ratio tells us that 2 moles of ClO2 react with 1 mole of H2O.

Now, we can calculate the theoretical amount of ClO2 and H2O that react based on the stoichiometry:

Theoretical amount of ClO2 = 2 moles of ClO2 / 2 * 67.45 g/mol
= 1.39 * 67.45 g
= 93.4 g

Theoretical amount of H2O = 1 mole of H2O / 1 * 18.02 g/mol
= 1 * 18.02 g
= 18.02 g

Since the theoretical amount of ClO2 is less than the actual amount, it is the limiting reactant. Therefore, it will be completely consumed in the reaction.

To find the remaining amount of ClO2 and H2O, we subtract the theoretical amount of ClO2 and H2O from their initial amounts:

Remaining amount of ClO2 = Initial amount of ClO2 - Theoretical amount of ClO2
= 142.0 g - 93.4 g
= 48.6 g

Remaining amount of H2O = Initial amount of H2O - Theoretical amount of H2O
= 33.0 g - 18.02 g
= 14.98 g

Therefore, after the reaction is complete, 48.6 grams of ClO2 and 14.98 grams of H2O will remain.