States of Matter
The substance that constitutes everything in the universe is known as matter. Matter comprises atoms which in turn are composed of electrons, protons, and neutrons. Different atoms combine together to give rise to molecules that act as a foundation for all kinds of substances. There are five states of matter based on their energies of attraction, namely solid, liquid, gases, plasma, and BEC (Bose-Einstein condensates).
Chemical Reactions and Equations
When a chemical species is transformed into another chemical species it is said to have undergone a chemical reaction. It consists of breaking existing bonds and forming new bonds by changing the position of electrons. These reactions are best explained using a chemical equation.
Consider the following reaction which occurs at constant temperature and pressure:
| 2 HI(g) H2(g) + I2(g) | H = 10.4 kJ |
Which has the higher enthalpy, 2 HI(g) or H2(g) + I2(g)?
Without referring to tables indicate which of each of the pairs of choices below has the higher enthalpy:
(a)
(b)
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