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3 years ago

At a recycling plant, old tin cans are melted down and reconstructed. This is an example of a _____

Chemistry

2 answers:

Len [333]3 years ago

5 0

Answer:

Physical change

Explanation:

Different types of changes take place. Two such changes are physical change and chemical change.

Physical change

This takes place when a substance changes from one state to another without changing the chemical composition. For example, water changes from liquid to solid (ice) when frozen. Thus, water has not changed its chemical properties. A physical change is reversible.

Thus, the melting of aluminium cans is a physical change.

Chemical change

This is a reaction that changes the original reactants to give different products. For example, burning coal gives ash, soot, carbon dioxide and water. Most chemical reactions are irreversible.

lina2011 [118]3 years ago

3 0

A change from physical change into chemical change not sure hope this helps

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Which term describes matter that is a substance made of diffrent kinds of atoms bonded together

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Compounds are substances made of at least 2 different elements. Molecules have at least 2 atoms, doesn't have to be different elements. Compounds and molecules both work.

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2 years ago

How do you think life on Earth would be different without the evolution of angiosperms? Provide two examples, each with an expla

IrinaVladis [17]

Answer:

Without angiosperms, average annual rainfall in the area declined by 300 millimeters. In the eastern Amazon basin, the length of the wet season decreased by nearly 3 months. The extent of the wettest rainforests, which receive more than 100 millimeters of rain per month, shrank by 80%.

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1 year ago

What is the pH of 0.26 M ammonium ion? NH4+(aq) + H2O(1) NH3(aq) + H30* (aq) a. 4.33 b.9.25 c. 3.87 d. 4.92 e. 4.75

choli [55]

Answer:

b) pH = 9.25

Explanation:

NH4+(aq) + H2O(l) ↔ NH3(aq) + H3O+(aq)
NH3 + H2O ↔ NH4+ + OH-
2 H2O ↔ H3O+ + OH-

⇒ Kb = [ NH4+ ] * [ OH- ] / [ NH3 ] = 1.86 E-5......from literature

mass balance NH4+:

⇒ M NH4+ = [ NH4+ ] - [ OH- ]

∴ [ NH3 ] ≅ M NH4+ = 0.26 M

⇒ Kb = (( 0.26 + [ OH- ] )) * [ OH- ] / 0.26 = 1.86 E-5

⇒ 0.26 [ OH-] + [ OH- ]² = 4.836 E-6

⇒ [ OH- ]² + 0.26 [ OH- ] - 4.836 E-6 = 0

⇒ [ OH- ] = 1.859 E-5 M

⇒ pOH = - Log ( 1.859 E-5 )

⇒ pOH = 4.7305

⇒ pH = 14 - pOH = 9.269

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2 years ago

How many mL of 1.50 M hydrochloric acid will neutralize 25 mL of 2.00 sodium hydroxide?

Lostsunrise [7]

Answer: The Answer is 18.7ml.

Explanation: Solved in the attached picture.

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2 years ago

Zinc reacts with hydrochloric acid according to the reaction equation Zn ( s ) + 2 HCl ( aq ) ⟶ ZnCl 2 ( aq ) + H 2 ( g ) How ma

REY [17]

Answer:

34.7mL

Explanation:

First we have to convert our grams of Zinc to moles of zinc so we can relate that number to our chemical equation.

So: 6.25g Zn x (1 mol / 65.39 g) = 0.0956 mol Zn

All that was done above was multiplying the grams of zinc by the reciprocal of zincs molar mass so our units would cancel and leave us with moles of zinc.

So now we need to go to HCl!

To do that we multiply by the molar coefficients in the chemical equation:

$\frac{0.0956g Zn}{1 } (\frac{2 mol HCl}{1molZn})$

This leaves us with 2(0.0956) = 0.1912 mol HCl

Now we use the relationship M= moles / volume , to calculate our volume

Rearranging we get that V = moles / M

Now we plug in: V = 0.1912 mol HCl / 5.50 M HCl

V= 0.0347 L

To change this to milliliters we multiply by 1000 so:

34.7 mL

7 0

3 years ago