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2 years ago

Which process is an example of a chemical change?

Chemistry

2 answers:

WARRIOR [948]2 years ago

8 0

Answer:

A is the closest thing. You change the composition of the steak. You don't in any of the others.

Explanation:

Usually when you cook something, you are doing something to the composition of the object being cooked. A steak might not be obvious, but boiling an egg should be.

Chopping a tree is something physical. You are removing mass in such a way that the tree will fall. There's nothing chemical about that.

Heating a cup of tea looks like it might be chemical. After all steam is sometimes given off which looks like it is chemical. It's not. The water in the tea is just changing phase.

Drying clothes in a dryer. Again, this looks like something might have changed. After all the mass of the clothes just became less. But all you are doing is separating two masses (leaving one of them behind).

aksik [14]2 years ago

6 0

A Sounds like the most relevant one

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3 years ago

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Given the following equation: 2K + Cl2 -> 2KCl How many grams of KCl is produced from 4.00 g of K and excess Cl2?

Thepotemich [5.8K]

Answer:

42.65g

Explanation:

Given parameters:

Mass of K = 4g

Unknown: Mass of KCl

Solution:

Complete equation of the reaction:

2K + Cl₂ → 2KCl

To solve this problem, we know that the reactant in short supply is potassium K and this dictates the amount of products that would be formed. The chlorine gas is in excess and we can't use it to determine the amount of product that would form.

Now, we work from the known to the unknown. Since we know the mass of K given in the reaction, we can simply find the molar relationship between the reacting potassium and the product. We simply convert the mass to mole and compare to the product. From there we can find the mass of KCl that would be produced.

Calculating number of moles of K

Number of moles = $\frac{mass}{molar mass}$

Number of moles of K = $\frac{4}{39}$ = 0.103mol

From the given reaction equation:

2 moles of K will produce 2 moles of KCl

Therefore 0.103mol of K will produce 0.103mol of KCl

To find the mass of KCl produced,

Mass of KCl = number of moles of KCl x molar mass

Molar mass of KCl = 39 + 35.5 = 74.5gmol⁻¹

Mass of KCl = 0.103 x 74.5 = 42.65g

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3 years ago

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2 years ago

23) What is the volume of 2.454 x 1024 atoms of nitrogen gas at STP?

earnstyle [38]

Answer:

d) V = 91.3 L

Explanation:

Given data:

Volume of nitrogen = ?

Temperature = standard = 273.15 K

Pressure = standard = 1 atm

Number of atoms of nitrogen = 2.454×10²⁴ atoms

Solution:

First of all we will calculate the number of moles of nitrogen by using Avogadro number.

1 mole = 6.022×10²³ atoms

2.454×10²⁴ atoms × 1 mol / 6.022×10²³ atoms

0.407×10¹ mol

4.07 mol

Volume of nitrogen:

PV = nRT

1 atm × V = 4.07 mol ×0.0821 atm.L /mol.K ×273.15 K

V = 91.3 atm.L /1 atm

V = 91.3 L

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If 6.0 x 10^23 atoms of aluminum weigh 27 g, calculate the mass of 1 atom of aluminum in picograms.

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Answer:

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Explanation:

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