Total internal energy change is equals to -44.83kJ
Q=-73.2kJ (negative sign indicates that heat was released by the system),
P= 50.0atm
ΔU= Q + W, FIRST LAW OF THERMODYNAMICS..........(1)
ΔV= Final volume - initial volume= 2.00 litre - 7.60litre= -5.60litre
work done by the system (w)= -PΔV
w= -(50.0×(-5.60)) atm×litre= 280atm litre
1 atm litre= 101.325J
w= 280 ×101.325 J= 28,371J
1kJ=1000J,
w=28.37KJ,
so putting in the values in equation (1)...
energy change(ΔU) = -73.2 kJ + 28.37 kJ
= - 44.83 kJ
The answer is a. triple beam balance
Balancing means there are equal amount of molecules on each side, both reactant and products. This is a method I like to do.
Under, I count how many molecules are in each side.
Cr2O3+Mg -->Cr + MgO
Cr: 2 1
O: 3 1
Mg: 1 1
Let's guess and make the number of oxygens equal on both sides.
Cr2O3+Mg -->Cr + 3MgO
Cr: 2 1
O: 3 3 EQUAL
Mg: 1 3
See what we did there? We multiplied the MgO on the products side by 3 so we can have 3 oxygens. Now let's multiply the Mg on the reactants by three so Mg AND O can be equal.
Cr2O3+3Mg -->Cr + 3 MgO
Cr: 2 1
O: 3 3 EQUAL
Mg: 3 3 EQUAL
Finally, we just need to multiply the loner Cr in the products side by two to make it equal for all elements.
Cr2O3+3Mg -->2Cr + 3 MgO
Answer:
The answer to this question is 3. Kinetic energy decreases as temperature decreases.
Explanation:
The average Kinetic energy is given by
× × T where
K = The average molecular kinetic energy of the gas (J)
= Boltzmann's constant (1.38× J/K)
T = Temperature of the gas in Kelvin (k)
When the temperature of a given mass of gas drops average kinetic energy of the molecules goes down and the average molecular speed decreases. The lower kinetic energy which is the energy of motion of the molecules indicates lower speed of the molecules.
Note that, the kinetic energy and average speed are related by the following formula
KE = ×m×v²
Where KE = Kinetic energy in Joules (J)
v = the velocity in m/s and
m = the mass of the molecule in Kg