Oxygen is prepared by heating KClO3.
(i) What weight of O2 is obtained from 3.00 g KClO3?
(ii) What is the volume of O2, measured at standard conditions?
(iii) What volume does the O2 occupy if collected over water at 0.961 atm
(i) Well, let's do some math with a touch of humor, shall we? To find the weight of O2, we first need to calculate the molar mass of KClO3. And let me tell you, KClO3 can't resist heating up! Its molar mass is 122.55 g/mol.
Now, since we have 3.00 g of KClO3, we can use some stoichiometry wizardry to find out the amount of O2 produced. According to the balanced equation, for every mole of KClO3, we get 3 moles of O2.
So, using the molar mass, we can convert 3.00 g KClO3 into moles and then multiply by 3 to find the moles of O2. Once we have that, it's just a matter of multiplying by the molar mass of O2 (32.00 g/mol). And voila, we have the weight of O2 obtained from our KClO3 bonanza!
(ii) Ah, comedy comes in all shapes, even in the form of volume calculations. Now, to determine the volume of O2 gas at standard conditions (which in this case means 1 atm pressure and 273 K temperature), we need to know the number of moles of O2.
Following our previous calculations, we already know the moles of O2. Now, all we need to do is apply the ideal gas law, PV = nRT. Under standard conditions, we have P = 1 atm, V is what we're trying to find, n is the number of moles, R is the universal gas constant (0.0821 L·atm/mol·K), and T is the temperature in Kelvin (273 K).
Plug in the values and solve for V. Tada! The volume of O2 gas at standard conditions shall be revealed!
(iii) Ah, collecting gas over water. It's like a bubbly adventure, isn't it? Now, to find the volume of O2 gas collected over water at a given pressure (0.961 atm in this case), we need to take into account the partial pressure of water vapor.
The total pressure of the collected gas is the sum of the pressure due to O2 gas and the pressure due to water vapor. In this case, the pressure due to water vapor is given, and we subtract it from the total pressure to find the pressure exerted by O2 gas alone.
Once we have that, we can use the ideal gas law again, PV = nRT, to find the volume of O2 gas at the given pressure. Remember to convert the pressure to atm and the temperature to Kelvin! And there you have it, a volume of O2 gas collected over water, ready to make some H2O bubbles jealous!
To determine the answers to these questions, we need to use stoichiometry and gas laws. Let's go through each question step by step:
(i) What weight of O2 is obtained from 3.00 g KClO3?
1. Start by writing the balanced chemical equation for the reaction:
2 KClO3 -> 2 KCl + 3 O2
2. Calculate the molar mass of KClO3:
K (39.10 g/mol) + Cl (35.45 g/mol) + 3 O (16.00 g/mol) = 122.55 g/mol
3. Calculate the number of moles of KClO3 present in 3.00 g:
moles of KClO3 = mass / molar mass = 3.00 g / 122.55 g/mol
4. According to the balanced equation, 2 moles of KClO3 produces 3 moles of O2. Therefore, the number of moles of O2 produced can be calculated using the mole ratio:
moles of O2 = moles of KClO3 x (3 moles O2 / 2 moles KClO3)
5. Calculate the mass of O2 produced using the molar mass of O2:
mass of O2 = moles of O2 x molar mass of O2
(ii) What is the volume of O2, measured at standard conditions?
1. Convert the mass of O2 obtained in question (i) to moles of O2 using the molar mass of O2.
2. Use the ideal gas law, 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, to calculate the volume of O2. At standard conditions, the pressure is 1.00 atm and the temperature is 273.15 K. Rearrange the equation to solve for V:
V = nRT / P
Plug in the values and calculate the volume of O2.
(iii) What volume does the O2 occupy if collected over water at 0.961 atm?
1. Subtract the vapor pressure of water at the given temperature from the total pressure to get the pressure of O2 gas alone:
O2 pressure = total pressure - vapor pressure of water
2. Use the ideal gas law, PV = nRT, to calculate the volume of O2:
V = nRT / P
Plug in the values, including the pressure of O2 obtained in step 1, and calculate the volume of O2 gas.