Answer:
Percentage Yield = 56.9% (to 3 significant figures)
Explanation:
Firstly you need to calculate the amount of moles of Na used. Moles = Mass/Mr, so moles of Na = 1.72x10^-3/23. This gets you 7.47826087x10^-5 moles.
The mole ratio of Na:Na2O is 2:1 so the moles of Na2O will be the moles of Na divided by 2. This gets you 3.739130435x10^-5 moles.
Mass = Moles x Mr
The Mr of Na2O = 62
Mass = 3.739130435x10^-5 x 62 = 2.31826087x10^-3g
Percentage Yield = (Actual Yield / Theoretical Yield) x 100
Percentage Yield = (1.32x10^-3 / 2.31826087x10^-3) x 100
Percentage Yield = 56.93923481%
Percentage Yield = 56.9% (to 3 significant figures)
Answer:
117.3 W is being removed.
Explanation:
The heat removed can be calculated as:
Q = m*c*ΔT
Where m is the mass, c is the specific heat and ΔT is the temperature variation. Because there're two components:
Q = mwater*cwater*ΔT + maluminum*caluminum*ΔT
Q = (mwater*cwater + maluminum*caluminum)*ΔT
Searching in a thermodynamic table:
cwater = 4.184 J/g°C
caluminium = 0.9 J/g°C
In 1 minute, the temperature decreases 2.2°C, so ΔT = -2.2°C
Q = (700*4.184 + 300*0.9) * (-2.2)
Q = -7037.36 J
The rate of energy is the potency (P), which is the heat divided by the time. So, for 1 minute (60 s):
P = -7037.36/60
P = -117.3 J/s
P = -117.3 W
The minus signal indicates that the energy is being removed.
Answer
is: mass number stays 184, but atomic number changes.<span>
Beta decay is radioactive decay in
which a beta ray and a neutrino are emitted from an atomic
nucleus.
There are two types of beta
decay: beta minus and beta
plus. In beta minus decay (</span>atomic number Z is increased by one, new element is wolfram W) neutron is converted to a
proton and an electron and
an electron antineutrino.
In beta
plus decay (atomic number Z is decreased by one, new element is hafnium Hf), a proton is converted to a neutron and positron and an electron neutrino, so mass number does not change.
First one is reactants and then second one is products
4I₂+9O₂= 2I₄+2O₉
Reactants: 8 iodine, 18 oxygen
Products: 8 iodine, 18 oxygen
Balanced!!
