Explain why H2O is a liquid while H^S is a gas at room temperature.
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Water exists as a liquid at room temperature with a high boiling point. Sulphur is less electronegative than oxygen, and the S-H bond is much less polar than the O-H bond.
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Hence, there is no hydrogen bonding in hydrogen sulphide, and it exists as a gas normally with discrete H2S molecules.
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At room temperature (anywhere from zero degree centigrade to 100 degrees centigrade), water is found in a liquid state. This is because of the tiny, weak hydrogen bonds which, in their billions, hold water molecules together for small fractions of a second. Water molecules are constantly on the move.