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3 years ago

The element oxidized in the reaction described in PbO2 + 4HCl → 2H2O + PbCl2 + Cl2 is A. Pb. B. O. C. H. D. Cl.

1 answer:

n200080 [17]3 years ago

4 0

For an element to be oxidized, its oxidation number would have to increase.

An element or compound's oxidation number is mainly dependent on its charge, except in special cases.

In PbO₂, Oxygen's oxidation number is always -2, except in hydrogen peroxide where it is -1. Since PbO₂ is neutral, its total oxidation number must be 0. Since there are two oxygens with an oxidation number of -2, we know that Pb's oxidation number is +4, since +4 -2×2 = 0.
Using the same method we can find Pb's oxidation number in PbCl₂. Unless paired with another halogen, which it isn't, Cl in a compound has an oxidation number of -1, so Pb = +2 since +2 -1×2 = 0.
Pb's oxidation number has gone from +4 to +2, so it has been reduced, so A. Pb is not the answer.

Oxygen in a compound's oxidation number is always -2 unless in H₂O₂ and it isn't on either side of the equation, so its oxidation number doesn't change and it remains in a compound, so B. O is not the answer.

Hydrogen in a compound's oxidation number is always +1, except in hydrides when it is -1, but it isn't, so it doesn't change , so C. H is the answer.

Therefore D. Cl is correct, since its oxidation number increases from -1 in HCl to 0 in Cl2 (since elements not in a compound have an oxidation number of 0)

Hope this helps!

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Which of the following is the best explanation for a covalent bond?

Scrat [10]

Answer:

A. electrons simultaneously attracted by more than one nucleus

Explanation:

Covalent bond is the bond which is formed with the sharing of the electrons between the two atoms which are taking part in the bond. It is generally formed between the atoms with similar electronegativity values.
It is the bond which is generally occurs within non metals as they share electrons to complete their octet.
The difference in the electronegativity values of the atoms involving in a covalent bond must not exceed the value of 1.7 .

Thus, the electrons are attracted by the two different nucleus of the atoms that are taking part in the bonding.

So, the correct answer is:- A. electrons simultaneously attracted by more than one nucleus

6 0

3 years ago

At 40.0°C, the pressure inside a nitrogen−filled tennis ball with a volume of 148 cm3 is 235 kPa. How many moles of nitrogen (N2

Musya8 [376]

To determine the number of moles of a gas, we need to have an expression that relates the pressure, temperature and volume of the system. For simplification, we assume that this gas is ideal so we use the equation PV=nRT. We calculate as follows:

PV=nRT
n = PV / RT
n = 235000(1.48x10^-4) / (8.314)(40+273.15)
n = 0.01336 mol

6 0

4 years ago

In the Mond process for the purification of nickel, carbon monoxide is reacted with heated nickel to produce Ni(CO)4, which is a

igor_vitrenko [27]

Answer: The equilibrium constant for this reaction is $1.068\times 10^{6}$

Explanation:

The equation used to calculate standard Gibbs free change is of a reaction is:

$\Delta G^o_{rxn}=\sum [n\times \Delta G^o_{(product)}]-\sum [n\times \Delta G^o_{(reactant)}]$

For the given chemical reaction:

$Ni(s)+4CO(g)\rightleftharpoons Ni(CO)_4(g)$

The equation for the standard Gibbs free change of the above reaction is:

$\Delta G^o_{rxn}=[(1\times \Delta G^o_{(Ni(CO)_4(g))})]-[(1\times \Delta G^o_{(Ni(s))})+(4\times \Delta G^o_{(CO(g))})]$

We are given:

$\Delta G^o_{(Ni(CO)_4(g))}=-587.4kJ/mol\\\Delta G^o_{(Ni(s))}=0kJ/mol\\\Delta G^o_{(CO(g))}=-137.3kJ/mol$

Putting values in above equation, we get:

$\Delta G^o_{rxn}=[(1\times (-587.4))]-[(1\times (0))+(4\times (-137.3))]\\\\\Delta G^o_{rxn}=-38.2kJ/mol$

To calculate the equilibrium constant (at 58°C) for given value of Gibbs free energy, we use the relation:

$\Delta G^o=-RT\ln K_{eq}$

where,

$\Delta G^o$ = Standard Gibbs free energy = -38.2 kJ/mol = -38200 J/mol (Conversion factor: 1 kJ = 1000 J )

R = Gas constant = 8.314 J/K mol

T = temperature = $58^oC=[273+58]K=331K$

$K_{eq}$ = equilibrium constant at 58°C = ?

Putting values in above equation, we get:

$-38200J/mol=-(8.314J/Kmol)\times 331K\times \ln K_{eq}\\\\K_{eq}=e^{13.881}=1.068\times 10^{6}$

Hence, the equilibrium constant for this reaction is $1.068\times 10^{6}$

4 0

3 years ago

2. How many moles of carbon dioxide, CO2, are in a 22 gram sample of the compound?

kotykmax [81]

To find the amount of moles in a molecule you divide the grams of the substance by the molar mass.
molar mass of CO2 = 44.01 g
22g / 44.01 = 0.50 moles CO2

4 0

3 years ago

What does subducted mean

vovikov84 [41]

The sideways and downward movement of the edge of a plate of the earths crust into the mantle beneath another plate

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4 years ago

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