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2 years ago

An example of a pure substance is ____.

Chemistry

1 answer:

Vsevolod [243]2 years ago

6 0

Answer: e) all of these

Explanation:

Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water $(H_2O)$ , carbon dioxide $(CO_2)$

Mixtures are not pure substances as they consist of elements and compounds combined physically and not in any fixed ratio. Example: Air

Thus all given substances are pure substances.

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What are the molality and mole fraction of solute in a 22.3 percent by mass aqueous solution of formic acid (HCOOH)?

Vanyuwa [196]

Answer:

Mole fraction for solute = 0.1, or 10%

Molality = 6.24 mol/kg

Explanation:

22.3% by mass → In 100 g of solution, we have 22.3 g of HCOOH

Mass of solution = 100 g

Mass of solute = 22.3 g

Mass of solvent = 100 g - 22.3g = 77.7 g

Let's convert the mass to moles

22.3 g . 1mol/ 46 g = 0.485 moles

77.7 g. 1mol / 18 g = 4.32 moles

Total moles = 4.32 moles + 0.485 moles = 4.805 moles

Xm for solute = 0.485 / 4.805 = 0.100 → 10%

Molality → mol/ kg → we convert the mass of solvent to kg

77.7 g. 1 kg / 1000g = 0.0777 kg

0.485 mol / 0.0777 kg = 6.24 m

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3 years ago

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Looking at the Lewis structure of SO2 attached to this answer, we can see the twelve valence electrons in the molecule and how they are distributed around each atom as shown.

Learn more: brainly.com/question/20514601

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