(Please explain the answer. Thank you!) A chemist needs 2.00 g of a liquid compound, which has a density of 0.718 g/mL. If the
compound costs $5.67 per mL, how much will a 2.00 gram sample cost?

Sample cost = $15.796

Given

Mass = 2 g

Density = 0.718 g/ml

Cost =  $5.67 per mL

Required

Cost

Solution

The density : the ratio of mass and volume

Can be formulated :

Density (ρ) = m : V

The volume of the liquid :

V = m : ρ

V = 2 g : 0.718 g/ml

V = 2.786 ml

Sample cost :

= 2.786 ml x $5.67/ml

= $15.796

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.