Chemistry, 23.10.2019 00:20 bikerhomie

Draw a cooling graph of water as it passes from 20°c to –20°c

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The graph will begin at 20 °C and have temperature on the y-axis and time on the x-axis. The line will be a downwards sloping one, until the value of temperature of the graph reaches 0 °C. There, it will become horizontal for a small amount of time, and then continue to slope downwards until the graph reaches -20 °C.

The horizontal region is where the freezing of water will take place, and there is no temperature change that occurs when a state change is taking place. This is because the energy involved then is latent energy.

Answer from: Quest

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form( $n_2$ ) .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

Answer from: Quest

"hydrogen bonding is the attraction of h atoms in the water molecule (slight + charge) to o atoms in a neighboring water molecule (slight - charge); it is a weak interatomic force. but it is still strong enough to the water molecules "stick" together."

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Draw a cooling graph of water as it passes from 20°c to –20°c...

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