Read the descriptions below of two substances and an experiment on each. Decide whether the result of the experiment tells you the substance is a pure substance or a mixture, if you can. Sample A is 100.mL of a clear liquid. The density of the liquid is measured, and turns out to be 0.77/gmL . The liquid is then cooled in the refrigerator. At 10.0°C crystals begin to appear until the liquid is about half crystal, half liquid. After 30 minutes, no more crystals appear, even though the temperature is lowered to 6.3°C Sample B is a solid yellow cube with a total mass of 50.0g . The cube is put into a pressure chamber and the pressure raised by pumping in nitrogen gas. At a pressure of 55.atm an orange liquid is observed seeping from the cube. After 30 minutes this flow stops, and the smaller and lighter-colored cube sits in a puddle of orange liquid without further change. Is sample A made from a pure substance or a mixture? If the description of the substance and the outcome of the experiment isn't enough to decide, choose "can't decide." mixture (can't decide) Is sample B made from a pure substance or a mixture? If the description of the substance and the outcome of the experiment isn't enough to decide, choose "can't decide." mixture (can't decide)
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.
Read the descriptions below of two substances and an experiment on each. Decide whether the result of the experiment tells you the substance is a pure substance or a mixture, if you can.
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Sample A is
of a clear liquid. The density of the liquid is measured, and turns out to be100.mL. The liquid is then cooled in the refrigerator. At0.77/gmLcrystals begin to appear until the liquid is about half crystal, half liquid. After10.0°Cminutes, no more crystals appear, even though the temperature is lowered to306.3°C -
Sample B is a solid yellow cube with a total mass of
. The cube is put into a pressure chamber and the pressure raised by pumping in nitrogen gas. At a pressure of50.0gan orange liquid is observed seeping from the cube. After55.atmminutes this flow stops, and the smaller and lighter-colored cube sits in a puddle of orange liquid without further change.30
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