How many grams of glucose, C 6H 12O 6, (molar mass 180.2 g/mol) must be added to 656 g water to raise the boiling point of water by 1.68 °C? K b of water is 0.512 °C/m.

We must add 387.9 grams of glucose

Explanation:

Step 1: Data given

Molar mass glucose = 180.2 g/mol

Mass of water = 656 grams

Boiling point will raise 1.68 °C

Kb of water = 0.512 °C/m

Step 2: Calculate molality

ΔT = i*kb * m

⇒ ΔT = The boiling point elevation = 1.68 °C

⇒ i = the van't Hoff factor = 1

⇒ Kb = The boiling point elevation constant = 0.512 °C/m

⇒ m = molality = moles glucose / mass water

m = 1.68 / 0.512 °C/m

m = 3.28125 molal

Step 3: Calculate moles glucose

Molality = moles glucose / mass water

3.28125 molal = moles glucose / 0.656 kg

Moles glucose = 2.1525 moles

Step 4: Calculate mass glucose

Mass glucose = moles glucose * molar mass glucose

Mass glucose = 2.1525 moles * 180.2 g/mol

Mass glucose = 387.9 grams

We must add 387.9 grams of glucose

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance