The addition of 117 g potassium fluoride to 599 ml of water (d = 1.00 g/ml) causes the temperature to rise 4.00 °c. what is the δhsoln for kf?

Answer : The for KF is -5.935 KJ/mole.

Solution : Given,

Mass of potassium fluoride = 117 g

Volume of water = 599 ml

Density of water = 1 g/ml

Molar mass of potassium fluoride = 58 g/mole

Temperature =

Specific heat capacity of water =

First we have to calculate the mass of solution.

Mass of water = Density × Volume = 1 × 599 = 599 g

Mass of solution = Mass of water + Mass of KF = 599 + 117 = 716 g

Now we have to calculate the heat absorbed by the solution.

Here, we assume that the specific heat capacity of the solution is the same as that of water.

Heat absorbed by the solution =

Heat absorbed by the solution =

Since the solution absorbed heat, the dissolution of KF must be exothermic and must have released

Now we have to calculate the moles of KF dissolved in solution.

Moles of KF =

Now we have to calculate the for KF.

Therefore, the for KF is -5.935 KJ/mole.

what does the table look like

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).