Consider an ice cube with a volume of 0.50 cup. (1 cup = 240.0 mL, density of ice = 0.9167 g/mL). How many water molecules (molar mass = 18.015 g/mol) are present in this ice cube?

3.86x10^24 molecules

Explanation:

From the question given, the following data were obtained:

Volume of ice = 0.5cup

1 cup = 240mL

0.5cup = 0.5 x 240 = 120mL

Density of ice = 0.9167 g/mL

molar mass of water = 18.015g/mol

First let us calculate the mass of ice. This is illustrated below:

Density = Mass /volume

Mass = Density x volume

Mass = 0.9167 x 120

Mass of ice = 110.004g = Mass of water

From Avogadro's hypothesis, we understood that 1mole of any substance contains 6.02x10^23 molecules. This means that 1mole of water will also contain 6.02x10^23 molecules.

1mole of water = 18.015g

If 1 mole (18.015g) contains 6.02x10^23 molecules,

Therefore, 110.004g of water will contain = (110.004x6.02x10^23)/18.015 = 3.86x10^24 molecules

b. is the answer hoped i        

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol