A35.6 g sample of ethanol (c2h5oh) is burned in a bomb calorimeter, according to the following reaction. if the temperature rose from 35.0 to 76.0°c and the heat capacity of the calorimeter is 23.3 kj/°c, what is the value of (change in enthalpy of reaction) dh°rxn ? the molar mass of ethanol is 46.07 g/mol.

Answer is: -1.24 x 103 kJ/mol the
The answer is right above so don't worry about reading all these.

reason why The heat capacity of the calorimeter is
c
=
23.3

k
J
/
o
C
,

and the change in temperature during the reaction is
Δ
T
=
76.0
−
35.0
o
C
=
41
o
C
.

The heat change during this combustion is:

Q
=
c
Δ
T
=
(
23.3

k
J
/
o
C
)
(
41
o
C
)
=
955.3

k
J
.

We burned 35.6 g of ethanol, whose molar mass is given as 46.07 g/mol. How many moles are these? We evaluate:

35.6

g
46.07

g
/
m
o
l
=
0.733

m
o
l
.

The enthalpy of reaction is therefore:

Δ
H
=
955.3

k
J
0.773

m
o
l
=
1236

k
J
/
m
o
l
.

Since this is an exothermic (heat-releasing) reaction, we conventionally introduce a negative sign and write:

Picture and explanation: C2H5OH(l) + O2(g) --> CO2(g) + H2O(g) ?H_ rxn = ?

-1.24 * 103 kJ/mol

+1.24 * 103 kJ/mol

-8.09 * 103 kJ/mol

-9.55 * 103 kJ/mol

+9.55 * 103 kJ/mol

Things you need to know: Enthalpy of Reaction
The enthalpy of a chemical reaction is the amount of heat released or absorbed when the reactants' bonds are broken and the products' bonds are formed. Exothermic reactions give off heat and are assigned a negative sign by convention, while endothermic ones absorb heat are carry a positive

Answer : option a) 84explanation :

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.