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3 years ago

Why does silver gate tarnish on exposed to air

Chemistry

2 answers:

Lelu [443]3 years ago

7 0

Answer:

when silver articles exposed to air silver racts with Sulphur present in the atmosphere and form a black layer of silver sulphide on the surface. copper articles get tarnished by reacting with air and water. due to this, a layer is formed over copper vessels.

stich3 [128]3 years ago

6 0

Explanation: When silver is exposed to sulfur-containing gases in the air, it discolours and then darkens as it reacts with the gas to form a surface layer of tarnish If a silver object is to be kept from tarnishing, it must be protected from sulfur-containing gases.

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A large deposit of bauxite a mineral containing aluminium was found in your community. The deposit crosses a nature preserve. A

Sophie [7]

Explanation:

One positive impact of the mining is that the sale of the Bauxite will increase their economic power by bringing in foreign exchange into their economy. This will improve services such as healthcare and infrastructure.

A negative impact is the destruction of the nature preserve and disturbing the ecosystem could lead to a devastating loss in biodiversity. A decrease in biodiversity will increase crop pests and diseases that destroy standing crops, and an increase in the prevalence of diseases in the community.

6 0

3 years ago

Hydrogen peroxide can act as either an oxidizing agent or a reducing agent depending on the species present in solution. Write t

Gekata [30.6K]

Answer:

Reduction: 2 H⁺(aq) + H₂O₂(aq) + 2 e⁻ ⇒ 2 H₂O(l)

Oxidation: H₂O₂(aq) ⇒ O₂(g) + 2 H⁺(aq) + 2 e⁻

Explanation:

In H₂O₂, hydrogen has the oxidation number +1 and oxygen the oxidation number -1.

In the reduction half-reaction (H₂O₂ is the oxidizing agent), H₂O₂ forms H₂O. The oxidation number of oxygen decreases from -1 to -2.

2 H⁺(aq) + H₂O₂(aq) + 2 e⁻ ⇒ 2 H₂O(l)

In the oxidation half-reduction (H₂O₂ is the reducing agent), H₂O₂ forms O₂. The oxidation number of oxygen increases from -1 to 0.

H₂O₂(aq) ⇒ O₂(g) + 2 H⁺(aq) + 2 e⁻

3 0

3 years ago

Phosphoric acid (h3po4) is tribasic, with pka's of 2.14, 6.86, and 12.4. The charge of the ionic form that predominates at ph 3.

Annette [7]

Correct answer is $H_2PO_4^-$ .

Phosphoric acid is a polyprotic acid having 3 acidic hyrdogen therefore it will have 3 pka values.

The equations for the release of acidic hydrogen can be written as:

$\\H_3PO_4\rightleftharpoons H_2PO_4^-+H^+\text{ pka=2.14}\\H_2PO_4^-\rightleftharpoons HPO_4^2^-+H^+\text{ pka=6.86}\\HPO_4^2^-\rightleftharpoons PO_4^3^-+H^+\text{ pka=12.4}$

From the pka values we can judge the idea of pH as using Henderson-Hasselbalch Equation, we get the relation between pH and pka.

$HA\rightarrow H^-+A^-$

Using the following equation, relation of pH and pka is

$pH=pka+log\frac{[A^-]}{HA}$

Using this equation, we can find that the equation having pka= 2. 14 is closest to the pH=3.2 so the ionic form in this equation will be dominant at the same pH.

Therefore at pH=3.2 the ionic form $H_2PO_4^-$ of $H_3PO_4$ is dominant.

7 0

3 years ago

Read 2 more answers

N2(g) + 3H2(g) →2NH3(g)

monitta

Answer:

2.5 moles of N₂ and 7.5 moles of H₂ entered the reaction

Explanation:

In reaction:

N₂(g) + 3 H₂(g) → 2 NH₃(g)

You can see that the stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction) requires the following amounts of reagents and are produced:

N₂: 1 mole
H₂: 3 moles
NH₃: 2 moles

The following three rules can apply:

If 2 moles of NH₃ are produced from 1 mole of N₂ by stoichiometry of the reaction, 5 moles of NH₃ from how many moles of N₂ are produced?

$moles of N_{2} =\frac{5 moles of NH_{3} *1 mole of N_{2} }{2 moles of NH_{3}}$

moles of N₂= 2.5

If 2 moles of NH₃ are produced from 3 moles of H₂ by stoichiometry of the reaction, 5 moles of NH₃ from how many moles of H₂ are produced?

$moles of H_{2} =\frac{5 moles of NH_{3} *3 mole of H_{2} }{2 moles of NH_{3}}$

moles of H₂= 7.5

<u><em>2.5 moles of N₂ and 7.5 moles of H₂ entered the reaction</em></u>

6 0

3 years ago

why polychromatic light gives continious spectrum if passes throught prism and why polychromatic light gives line spectrum when

alukav5142 [94]

Answer:

I don’t know

Explanation:

4 0

3 years ago