A0.250-g chunk of sodium metal is cautiously dropped into a mixture of 50.0 g of water and 50.0 g of ice, both at 08c. the reaction is 2na(s) 1 2h2o(l) 88n 2naoh(aq) 1 h2(g) dh 5 2368 kj

The ice will not melt

Explanation:

Given:

Mass of chunk = 0.25 g

moles of sodium = mass / molar mass = 0.25 / 23 = 0.010 g

ΔH = -368 KJ

Hence, 2 moles of Na produced 368 KJ

So 1 mole will produce 368 / 2 KJ and 0.01 mole will produce

= (368 / 2) * 0.01 = 2.0056 KJ

Also, moles of ice = mass / molar mass of water = 50 / 18 = 2.8 g

Energy required to melt the ice = enthalpy of fusion of ice * number of moles of ice

= 6.01 * 2.8 = 16.722 KJ

But we have 2.0056 KJ, so the ice will not melt.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e