In the reaction: P4 (S) +Cl2 (g)PCl5(s),
1. If you have 10.00 grams of Phosphorus to react with 220 grams of Chlorine
gas, what would be the theoretical yield of PCl5(s), in grams?
2. Why was there condensation of the beaker of cold water when a blue flame
was passes underneath?
(A) the product of carbon dioxide from combustion
(B) the product of hydrogen dioxide from combustion
(C) left over unburned oxygen
(D) left over unburned methane
(E) melting of the glass
3. The reaction of hydrogen peroxide in the presence of manganese dioxide produces:
(A) carbon dioxide
(B) oxygen
(C) hydrogen gas
(D) nitrogen dioxide
(E) methane
4. A 21.18 mL of 0.250 M NaOH is titrated with a H2SO4 solution. The initial volume of H2SO4 was 13.28 and the final volume of H2SO4 was 28.29 mL when the solution turned very slightly pink. What is the concentration of Ca(OH)2?
5. You know the solution forms a precipitate when:
(A) when it changes color
(B) when you can’t see through it
(C) because it bubbles
(D) you have stirred it for more than 5 minutes
(E) the solution thickens
1. Write the equation and balance it.
P4 + 10Cl2 ==> 4PCl5
2a. Convert grams P to moles. mole = grams/molar mass
2b. Convert g Cl2 to mole. Same process.
3a. Using the coefficients in the balanced equation, convert moles P to moles product.
3b. Same procedure, convert moles Cl2 to moles product.
3c. It is likely that moles product from 3a and 3b will not agree which means one of them is wrong. The correct value, in limiting reagent problems, is ALWAYS the smaller one and the reagent producing that value is the limiting regent.
4. Now use the smaller value from 3c and convert to grams. g = moles x molar mass. This is the theoretical yield.
#2. I have no idea what you are talking about in #2.
#3.oxygen
#4. You need to read #3 and make changes. M Ca(OH)2 is zero the way I see it; you didn't start with any.
#5. I don't know what you are doing in the experiment.
#4.
1. To determine the theoretical yield of PCl5 (s), you need to use stoichiometry and the given amounts of reactants.
First, convert the mass of phosphorus (P4) to moles by using the molar mass of phosphorus. Since the molar mass of P4 is 123.895 g/mol, divide the given mass (10.00 g) by the molar mass:
10.00 g P4 / 123.895 g/mol = 0.0807 mol P4
Next, convert the mass of chlorine gas (Cl2) to moles using the molar mass of chlorine. The molar mass of Cl2 is 70.906 g/mol, so divide the given mass (220 g) by the molar mass:
220 g Cl2 / 70.906 g/mol = 3.10 mol Cl2
Next, determine the limiting reactant by comparing the mole ratios between phosphorus and chlorine. From the balanced equation, the mole ratio of P4 to Cl2 is 1:5.
Since there are fewer moles of phosphorus (0.0807 mol) compared to chlorine (3.10 mol), phosphorus is the limiting reactant.
The theoretical yield is determined by the stoichiometry of the balanced equation. From the balanced equation: P4 (s) + Cl2 (g) → PCl5 (s), the mole ratio of P4 to PCl5 is 1:1.
Therefore, 0.0807 mol of P4 will produce 0.0807 mol of PCl5.
Finally, calculate the mass of PCl5 using the molar mass of PCl5 (208.225 g/mol):
0.0807 mol PCl5 x 208.225 g/mol = 16.85 g PCl5 (rounded to two decimal places)
So, the theoretical yield of PCl5 (s) is 16.85 grams.
2. The condensation of the beaker of cold water when a blue flame is passed underneath is due to the product of water vapor (H2O) from combustion. When the blue flame is passed over or near a cold surface, it cools down the surrounding air, causing the water vapor present in the air to condense back into liquid water, resulting in the formation of condensation. Therefore, the correct answer is (A) the product of water (H2O) from combustion.
3. The reaction of hydrogen peroxide (H2O2) in the presence of manganese dioxide (MnO2) produces oxygen gas (O2). The balanced chemical equation for this reaction is:
2 H2O2 (aq) → 2 H2O (l) + O2 (g)
Therefore, the correct answer is (B) oxygen gas.
4. To determine the concentration of Ca(OH)2, you need to use the concept of stoichiometry and the data from the titration.
First, write the balanced equation for the reaction between NaOH and H2SO4:
H2SO4 (aq) + 2 NaOH (aq) → Na2SO4 (aq) + 2 H2O (l)
From the balanced equation, you can see that the stoichiometric ratio between H2SO4 and NaOH is 1:2. So, 1 mole of H2SO4 reacts with 2 moles of NaOH.
Use the given data from the titration:
Initial volume of H2SO4 = 13.28 mL
Final volume of H2SO4 = 28.29 mL
Calculate the volume of H2SO4 used in the titration:
Volume of H2SO4 used = Final volume - Initial volume
= 28.29 mL - 13.28 mL
= 15.01 mL
Now, use the molarity and volume data to calculate the number of moles of H2SO4 used:
Moles of H2SO4 = Molarity × Volume (in liters)
= 0.250 M × (15.01 mL / 1000 mL/liter)
= 0.0037525 mol H2SO4
Since the stoichiometric ratio between H2SO4 and NaOH is 1:2, the number of moles of NaOH used in the titration is twice that of H2SO4:
Moles of NaOH = 2 × Moles of H2SO4
= 2 × 0.0037525 mol NaOH
= 0.007505 mol NaOH
Now, calculate the concentration of NaOH by dividing the moles of NaOH by the volume in liters:
Concentration of NaOH = Moles of NaOH / Volume (in liters)
= 0.007505 mol NaOH / (21.18 mL / 1000 mL/liter)
= 0.3538 M NaOH
Therefore, the concentration of Ca(OH)2 is 0.3538 M.
5. Precipitation occurs when two solutions are mixed and a solid substance is formed and separates from the solution. This can be observed by a change in appearance such as cloudiness or the formation of visible solid particles suspended in the solution. Therefore, the correct answer is (B) when you can't see through it, indicating the formation of a precipitate.