Answer: The energy of the 4-s subshell is lower than the energy of 3-d subshell.
Explanation:
During the filling of electrons in subshells, the lower energy levels are filled before the higher energy levels. Also known as Aufbau principle.
Energy of the sublevel = (n + l)
where : n = Principal quantum number
l = Azimuthal quantum number(s=0,p=1,d=2,f=3)
Energy of 4-s subshell= (4+0) = 4
Energy of 3-d subshell=(3+2) = 5
Energy of 4-s subshell is lower than the energy of 3-d subshell, that is why 4s orbital is filled before the 3-d subshell.
Convert mole to gram by multiplying the molar mass of sodium
0.500mol Na x 22.990g = 11.495g of Na
Answer:
1. 80g
2. 1.188mole
Explanation:
1. We'll begin by obtaining the molar mass of CH4. This is illustrated below:
Molar Mass of CH4 = 12 + (4x1) = 12 + 4 = 16g/mol
Number of mole of CH4 from the question = 5 moles
Mass of CH4 =?
Mass = number of mole x molar Mass
Mass of CH4 = 5 x 16
Mass of CH4 = 80g
2. Mass of O2 from the question = 38g
Molar Mass of O2 = 16x2 = 32g/mol
Number of mole O2 =?
Number of mole = Mass /Molar Mass
Number of mole of O2 = 38/32
Number of mole of O2 = 1.188mole
Since the density of water is 1 g /mL, hence there is 100
g of H2O. So total mass is:
m = 100 g + 5 g = 105 g
=> The heat of reaction can be calculated using the
formula:
δhrxn = m C ΔT
where m is mass, C is heap capacity and ΔT is change in
temperature = negative since there is a decrease
δhrxn = 105 g * 4.18 J/g°C * (-2.30°C)
δhrxn = -1,009.47 J
=> However this is still in units of J, so calculate
the number of moles of NaCl.
moles NaCl = 5 g / (58.44 g / mol)
moles NaCl = 0.0856 mol
=> So the heat of reaction per mole is:
δhrxn = -1,009.47 J / 0.0856 mol
δhrxn = -11,798.69 J/mol = -11.8 kJ/mol
