All categories

2 years ago

Is silver tarnishing a physical change or a chemical change?

Chemistry

1 answer:

Shalnov [3]2 years ago

6 0

Answer:

chemical

Explanation:

Some bronze objects tarnish to a dark brown color. Chemical properties can be identified by the changes they produce. The change of one substance into another substance is called a A piece of wood burning, an iron fence rusting, and a silver spoon tarnishing are all examples of chemical changes.

You might be interested in

Consider the reaction of 19.0 g of zinc metal with excess silver nitrate to produce silver metal and zinc nitrate. The reaction

Alexeev081 [22]

Answer:

14.5 g silver

Explanation:

This is a problem using the stoichiometry of the reaction. First thing we need is the balanced equation:

Zn + 2 AgNO3 ----------------------- 2 Ag + Zn(NO3)2

We know that 14.6 g of Zn did not reacted, then we can calculate the amount of Zn reacted and do the calculation given the above reaction.

amount Zn reacted: 19.0 -14.6 g Zn = 4.4 g Zn

atomic weight of Zn: 65.37 g/mol

mol Zn reacted: 4.4 g Zn x ( 1 mol Zn/ 65.37 g Zn) = 0.067 mol Zn

We know from the balanced equation that moles of Ag are produced from 1 mol Zn therefore the mol of Ag produced are:

0.067 mol Zn x 2 mol Ag/ 1mol Zn = 0.135 mol Ag

and the mass of silver then will be given by multiplying by the atomic weight of silver:

0.135 mol Ag x 107.9 g/mol = 14.5 g Ag

4 0

3 years ago

Useful: Harmful: 2. Give an example of how Bacteria can be useful and harmful to man.

kupik [55]

Answer:

normal flora useful

Explanation:

protect the skin

5 0

3 years ago

You are given a solid that is a mixture of na2so4 and k2so4.

Murljashka [212]

Here we have to calculate the amount of $SO_{4}^{2-}$ ion present in the sample.

In the sample solution 0.122g of $SO_{4}^{2-}$ ion is present.

The reaction happens on addition of excess BaCl₂ in a sample solution of potassium sulfate (K₂SO₄) and sodium sulfate [(Na)₂SO₄] can be written as-

K₂SO₄ = 2K⁺ + $SO_{4}^{2-}$

(Na)₂SO₄=2Na⁺ + $SO_{4}^{2-}$

Thus, BaCl₂+ $SO_{4}^{2-}$ = BaSO₄↓ + 2Cl⁻ .

(Na)₂SO₄ and K₂SO₄ is highly soluble in water and the precipitation or the filtrate is due to the BaSO₄ only. As a precipitation appears due to addition of excess BaCl₂ thus the total amount of $SO_{4}^{2-}$ ion is precipitated in this reaction.

The precipitate i.e. barium sulfate (BaSO₄)is formed in the reaction which have the mass 0.298g.

Now the molecular weight of BaSO₄ is 233.3 g/mol.

We know the molecular weight of sulfate ion ( $SO_{4}^{2-}$ ) is 96.06 g/mol. Thus in 1 mole of BaSO₄ 96.06 g of $SO_{4}^{2-}$ ion is present.

Or. we may write in 233.3 g of BaSO₄ 96.06 g of $SO_{4}^{2-}$ ion is present. So in 1 g of BaSO₄ $\frac{96.06}{233.3}=0.411$ g of $SO_{4}^{2-}$ ion is present.

Or, in 0.298 g of the filtered mass (0.298×0.411)=0.122g of $SO_{4}^{2-}$ ion is present.

5 0

3 years ago

If 1.546 g of copper was used by a student at the start of the lab, and 0.732 g of copper were obtained at

mash [69]

Answer: Percent recovery is 47.34 %

Explanation:

Percent yield is defined as the ratio of experimental yiled to theoretical yield in terms of percentage.

${\text{ percent yield}}=\frac{\text{amount recovered}}{\text{total amount}}\times 100$

Putting in the values we get:

${\text{ percent yield}}=\frac{0.732}{1.546}\times 100=47.34\%$

Therefore, the percent recovery is 47.34 %

8 0

2 years ago

How does water vapor become frost?

Tatiana [17]

Frost forms when an outside surface cools past the dew point. The dew point is the point where the air gets so cold, the water vapor in the atmosphere turns into liquid. This liquid freezes. If it gets cold enough, little bits of ice, or frost, form. google

6 0

3 years ago

Is silver tarnishing a physical change or a chemical change?​

Is silver tarnishing a physical change or a chemical change?