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‼️I have balanced the EQ already, but I'm lost on part B. will be awarding all my points (100+) to someone who can help and provide steps :) ‼️

Mrs. Webb placed a cup containing 10.0 g of water into a beaker, then placed 2.0 g of calcium carbide, CaC₂ into the H₂O. The reaction produced flammable ethyne (C₂H₂) gas an calcium hydroxide.
a. Write the balanced equation for the reaction. CaC₂+ H₂O → C₂ H₂ + Ca(OH)₂
b. How many L of ethyne (at STP) can form?​

User Srcerer
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1 Answer

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Step-by-step explanation:

To determine how many liters of ethyne (C₂H₂) can form at STP, we need to use stoichiometry and the ideal gas law.

First, let's determine the number of moles of CaC₂ and H₂O that reacted. From the given information, we know that the mass of water is 10.0 g and the mass of CaC₂ is 2.0 g. We can use the molar masses of CaC₂ (64.10 g/mol) and H₂O (18.02 g/mol) to convert the masses to moles:

moles of CaC₂ = 2.0 g / 64.10 g/mol = 0.0312 mol

moles of H₂O = 10.0 g / 18.02 g/mol = 0.555 mol

Next, we need to determine the limiting reactant to find out how many moles of ethyne can form. To do this, we compare the mole ratio of CaC₂ to H₂O in the balanced equation:

CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂

1 2

For every 1 mole of CaC₂, we need 2 moles of H₂O to react. The moles of H₂O we have (0.555 mol) are more than enough to react with the moles of CaC₂ we have (0.0312 mol). Therefore, CaC₂ is the limiting reactant.

Now we can use the mole ratio of CaC₂ to C₂H₂ in the balanced equation to find the moles of C₂H₂ that can form:

CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂

1 1

1 mole of CaC₂ produces 1 mole of C₂H₂. Therefore, the moles of C₂H₂ that can form is also 0.0312 mol.

Finally, we can use the ideal gas law to find the volume of C₂H₂ at STP. The ideal gas law is PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature. At STP, the pressure is 1 atm and the temperature is 273 K.

Plugging in the values, we get:

V = (nRT) / P

V = (0.0312 mol)(0.0821 L·atm/mol·K)(273 K) / 1 atm

V = 0.738 L

Therefore, the volume of C₂H₂ that can form at STP is 0.738 L.

User Apmccartney
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