The energy released when Na+(g) and Cl- (g) form NaCl(s) is 778. kJ/mol. Approximately 162. J is absorbed from the surroundings when 2.35 g of NaCl is completely dissolved in water. What is the enthalpy of hydration of NaCl?


Answer 1

Answer: -777.838


Given data,

Lattice energy (energy released to form NaCl )= 778 kJ/mol

Heat of solution = 162 Joules

                                 = 0.162 kJ (converted to kilojoules)

Substitute the values in the given formula,

Enthalpy of hydration = ΔHsolution – ΔHlattice energy

                            = 0.162 – 778

Therefore, Enthalpy of hydration = -777.838

Related Questions


50 grams of propane is placed into a bomb calorimeter at 20 deg C.It is found that the heat released is 50 kj. What is the temperature of the system? The heat capacity of the cariometer is 6.00 kj/C


The final temperature is 28 °C.

There are two heat transfers involved.

heat from combustion of propane + heat gained by water = 0

q_1 + q_2 = 0

q_1+ C_calΔT = 0

q_1 = -50 kJ

q_2 = 6.00 kJ·°C^(-1)  × ΔT = 6.00 ΔT kJ·°C^(-1)

q_1 + q_2 = -50 kJ + 6.00 ΔT kJ·°C^(-1) = 0

ΔT = 50/[6.00 °C^(-1)] = 8.33 °C

T_f = T_i + ΔT = 20 °C + 8.33 °C = 28 °C


You can use mole ratios and molar mass to determine the masses of substances involved in a chemical reaction. Using the periodic table, calculate the molar masses of iron oxide (Fe2O3) and aluminum oxide (Al2O3). Give your answer to four significant figures. Molar mass of Fe2O3 =



1st one is 159.7

2nd is 102.0


The guy above me is right



An unknown, clear liquid is given to you in a beaker. You transfer some of the liquid from the beaker to a clean, empty test tube, and begin to heat it. Soon, you observe a vapour leaving the top of the test tube. With further analysis you discover that the vapour is water vapour. Eventually, all that's left are a few crystals stuck to the sides of the test tube. Was the original liquid an element, a compound, or a mixture? Explain


A mixture because there was residue left at the bottom of the test tube and another substance that evaporated meaning that there was more than one thing in the test tube.
A mixture because there was remaining  left at the bottom of the test tube and another substance that evaporated meaning that there was a lot more than one thing in the tube 

Which of these observations is not an example of a physical property of matter? A. The density of sea water is measured to be 1.027 g/cm3. B. Gold melts at 1064 ºC.
C. There are usually at least three different minerals in a piece of granite.
D. Your mother's best silver tarnishes.



D. Your mother's best silver tarnishes.



In this case, the answer is: D. Your mother's best silver tarnishes, since tarnishing is a process carried out due to the effect of an external condition (aging, wearing out and others), not a property. Properties are actually descripted on options A, B and C as they describe the material in terms of its nature.

Best regards.

D... i feel bad that you didnt understand this...
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