4. The cooling curve below represents the uniform cooling of a substance, starting at a temperature above its boiling point.
Cooling Curve
5
Temperature (°C)
1
1
1
!
1
i
.
1
1
1
1
0
1
2
3
4
5
6
7
8
9
10
11
Time (min)
During which time interval does the substance exist as both a liquid and a gas?
(1) min 2 to min 4
(2) min 2 to min 6
(3) min 5 to min 7
(4) min 7 to min 9
6

Which of the following signs of a chemical reaction are observed in the reaction of potassium with water? precipitate formed temperature change smell produced gas produced color change

There are two steps in the usual industrial preparation of acrylic acid, the immediate precursor of several useful plastics. in the first step, calcium carbide and water react to form acetylene and calcium hydroxide: cac2 (s) + 2h2o (g) → c2h2 (g) + caoh2 (s) =δh−414.kj in the second step, acetylene, carbon dioxide and water react to form acrylic acid: 6c2h2 (g) + 3co2 (g) + 4h2o (g) → 5ch2chco2h (g) =δh132.kj calculate the net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxide from these reactions. round your answer to the nearest kj .

How many moles of no2 will form when 3.3 moles of cu are reacted with excess hno3?