<h3>
Answer:</h3>
498 kj/mol
<h3>
Explanation:</h3>
- Chemical reactions occur as a result of bond breaking and bond formation.
- The bonds in reactants are broken and atoms are rearranged to form new bonds.
- During bond breaking energy is absorbed to break the bonds of reactants while bond formation involves the release of energy during the formation of new bonds.
In our case;
In 1 mole of the Oxygen molecule, there is one O=O bond
Energy absorbed to break O=O is 498 kJ/mol
Therefore, the ΔH required to break all the bonds in one mole of Oxygen(O₂) molecules is 498kJ/mol.
Note that, bond breaking is endothermic since energy is absorbed from the surroundings.
Explanation:
A substance burning in the presence of oxygen and leads to the formation of heat and light is called combustion.
Some important points about combustion are as follows:
- Fuel should be present for burning.
- Air should be present for the supply of oxygen.
- There should be heat (or ignition temperature) to initiate the chemical reaction.
The molecular formula of chlorofluorocarbon is CF₂Cl₂
Molecular mass of CF₂Cl₂ is 120.9 g/mol
Mass of Cl in 1 mol - 2 x 35.5 = 71 g/mol
in 120.9 g of compound - 71 g of Cl
Therefore in 38 g of sample - 71/120.9 x 38 g of Cl
Mass of Cl in 38 g - 22.31 g of Cl
To improve the efficiency of fireplaces, technologies such as A. addition of catalytic combustors and B. <span>addition of boilers are used in so far. Addition of catalytic combustors hastens the process and makes use of inerts that cannot be used. The addition of boilers also adds to the efficiency by converting fluids to higher temperatures,</span>
K2Cr2O7 + 14HCl → 2CrCl3 + 2KCl + 3Cl2 + 7H2O
the correct option is :
K2Cr2O7, because the oxidation number of Cr changes from +6 to +3.
<u>Oxidation number of Cr in K2Cr2O7 is:</u>
K2Cr2O7 = 2K + 2 Cr + 7 O
= 2(+1) + 2Cr + 7(-2)
= 2 + 2Cr -14
[total charge on K2Cr2O7 = 0], Hence;
2 + 2Cr -14 = 0
2Cr -12 = 0
2Cr = 12
Cr = 12/2
<u>Cr = +6</u>
<u>Oxidation number of Cr in CrCl3 is:</u>
CrCl3 = Cr + 3Cl = 0
Cr + 3(-1) = 0
Cr -3 = 0
<u>Cr = +3</u>
Hence Cr is changing its oxidation number from
+6 in K2Cr2O7 to +3 in CrCl3.
Since the oxidation number of Cr [ +6 → +3] is decreasing here,
Cr is getting reduced.
so K2Cr2O7 is an oxidizing agent,as it is getting itself reduced and oxidizes others.
