If you calculated the concentration of β-carotene in your 2.50 mL sample to be 2.209×10−6 M, how many grams of β-carotene are in your sample? The molar mass of β-carotene is 536.85 g/mole.

Mass β-carotene = 0.000002964754125 grams = 0.002964754125 mg = 2.964754125 µgrams

Explanation:

Step1: Data given

Volume = 2.50 mL = 0.0025 L

Molarity = 2.209 * 10^-6 M

The molar mass of β-carotene is 536.85 g/mol

Step 2: Calculate moles β-carotene

Moles β-carotene  = molarity * volume

Moles β-carotene = 2.209 * 10^-6 M * 0.0025 L

Moles β-carotene = 0.0000000055225 = 5.5*10^-9 moles

Step 3: Calculate mass of β-carotene

Mass β-carotene = moles β-carotene ¨molar mass β-carotene

Mass β-carotene = 5.5*10^-9 moles *536.85 g/mol

Mass β-carotene = 0.000002964754125 grams = 0.002964754125 mg = 2.964754125 µgrams

in the given question, the partial pressure is calculated by using the ideal gas equation, that is, pv = nrt

here, p is pressure, v is volume = 25 l, n is number of moles = 0.0104 moles, r is gas constant = -0.0821 l.atm / mol.k

t is temperature = 273 k

p = nrt / v

p = (0.0104 mol × 0.0821 l.atm / mol.k × 273 k) / 25 l

= 0.0093 atm

the answer is option a.