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

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.