During a phase change the temperature does not change since all of the heat is being absorbed in order to break the intermolecular forces. Due to that, the formula will not need to have T in it and is actually q=nΔH(v).
n=the number of moles (in this case 2.778mol of water since you divide 50g by 18g/mol).
ΔH(v)=the molar heat of vaporization (in this case 40.7kJ/mol).
q=the heat that must be absorbed
q=2.778mol×40.7kJ/mol
q=113.1kJ
Therefore the water needs to absorb 1.13×10²kJ.
I hope this helps. Let me know if anything is unclear.
Answer:
2023.04 g
Explanation:
Magnetite reacts with hydrogen to produce Iron metal and steam. Steam instead of water is produced as the reaction occurs at temperatures above the boiling point of water.
Fe₃O₄ + 4 H₂ → 3 Fe +4 H₂O
From the equation, 1 mole of Fe₃O₄ reacts with 4 moles of H₂.
69.76 grams of H₂ has the following number of moles.
Number of moles= mass/RAM
=69.76/2
=34.88 moles.
The reaction ratio of Fe₃O₄ to H₂ is 1:4
Thus number of moles of magnetite= (1×34.88)/4
=8.72 moles.
Mass= moles × molecular weight
=8.72 moles × (56×3+16×4)
=2023.04 grams
One thing to notice in the question is, we are asked about molecular oxygen that has formula O2 not atomic oxygen O.
As we are asked about molecular oxygen, we will answer the question in terms of number of molecules that are present in 16 grams of molecular oxygen.
To get the number of molecules present in 16 grams of O2, we will use the formula:
No. of molecules = no. of moles x Avogadro's number (NA)----- eq 1)
As we know:
The number of moles = mass/ molar mass of molecule
Here we have been given mass already, 16 grams and the molar mass of O2 is 32 grams.
Putting the values in above formula:
= 16/32
= 0.5 moles
Putting the number of moles and Avogadro's number (6.02 * 10^23) in eq 1
No. of molecules = 0.5 x 6.02 * 10^23
=3.01 x 10^23 molecules
or 301,000,000,000,000,000,000,000 molecules
This means that 16 grams of 3.01 x 10^23 molecules of oxygen.
Hope it helps!
It’s, D. Kinetic Energy.
Explanation: Energy associated with an object’s motion is called kinetic energy. A speeding bullet, a walking person, and electromagnetic radiation like light all have kinetic energy.
Hope this helped ;)
Answer: 94.13 L
Explanation: In STP in an ideal gas there is a standard value for both temperature and pressure. At STP,pressure is equal to 1atm and the temperature at 0°C is equal to 273.15K. This problem is an ideal gas so we use PV=nRT where R is a constant R= 0.08205 L.atm/mol.K.
To find volume, derive the equation, it becomes V=nRT/P. Substitute the values. V= 4.20 mol( 0.08205L.atm/mol.K)(273.15K) / 1 atm = 94.13 L. The mole units, atm and K will be cancelled out and L will be the remaining unit which is for volume.
