Answer:
- second choice:<em><u> 1.0 g of the solution contains 15 × 10⁻⁶ g of benzene.</u></em>
Explanation:
ppm is a unit of concentration that means parts per million. In grams that is grams of solute per one million (10⁶) grams of solution.
Then, <em>15 ppm of benzene</em> means that there are 15 grams of benzen in 1,000,000 grams of solution.
That leads to:
- 1,000,000 g solution / 15 g benzene
Multiplying numerator and denominator by 10⁻⁶ you find:
- 1,000,000 × 10⁻⁶ g solution / (15 × 10⁻⁶ g benzene)
Simplifying:
- 1.0 g solution / (15 × 10⁻⁶ g benzene)
Which is read as 1.0 g of the solution contains 15 × 10⁻⁶ g of benzene, i.e. the second answer choice.
Agar is extracted from an algae (agarophytes, <span>belong to the </span>Rhodophyta (red algae) phylum, <span>primarily from the </span>genera Gelidium<span> and </span><span>Gracilaria</span>).
Agar <span>or </span>agar-agar is a jelly-like substance. Agar is the mixture of two components, agaropectin (D-glucuronic acid and pyruvic acid) and <span>the polysaccharide agarose.</span>
Answer:
3.82 x 10²¹ molecules As₂O₃
Explanation:
To find the amount of molecules arsenic (III) oxide (As₂O₃), you need to (1) convert kg to lbs, then (2) convert g As₂O₃ to moles As₂O₃ (via molar mass), and then (3) convert moles to molecules (via Avogadro's number).
1 kilogram = 2.2 lb
Molar Mass (As₂O₃): 2(74.992 g/mol) + 3(15.998 g/mol)
Molar Mass (As₂O₃): 197.978 g/mol
Avogadro's Number:
6.022 x 10²³ molecules = 1 mole
0.0146 g As₂O₃ 1 kg 189 lb
------------------------ x --------------- x ------------------ x ................
1 kg 2.2 lb
1 mole 6.022 x 10²³ molecules
x ------------------ x --------------------------------------- = 3.82 x 10²¹ molecules As₂O₃
197.978 g 1 mole
