1. Identify each of the following as an example of a chemical change or physical change. A. Moisture in the air forms beads of water on a cold windowpane. B. An electric current changes water into hydrogen and oxygen. C, Yeast cells in bread dough may carbon dioxide and ethanol from sugar. D. Olive oil, vinegar, salt, and pepper are shaken together to make salad dressing. E. Molten bronze is poured into a mold and solidifies to form a figurine. F. A reactant decomposes to form two products.
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.
![Changes in Matter Practice Problems
1. Identify each of the following as an example of a chemical change or physical
change.
A. Moisture in the air forms beads of water on a cold windowpane.
B. An electric current changes water into hydrogen and oxygen.
C, Yeast cells in bread dough may carbon dioxide and ethanol from sugar.
D. Olive oil, vinegar, salt, and pepper are shaken together to make salad
dressing.
E. Molten bronze is poured into a mold and solidifies to form a figurine.
F. A reactant decomposes to form two products.
2. A sealed glass tube contains 2.25 g of copper and 3.32 g of sulfur. The mass of
the tube and its contents is 18.48 g. Upon heating, a reaction forms copper (II)
sulfide (CuS). All of the copper reacts, but only 1.14 g of sulfur reacts. Predict
what the mass of the tube and its contents will be after the reaction is completed.
Explain your reasoning.
3. When heated, calcium hydroxide and ammonium chloride react to produce
ammonia gas, water vapor, and solid calcium chloride. Suppose 5.0o g of calcium
hydroxide and 10.00 g of ammonium chloride are mixed in a test tube and heated
until no more ammonia is given off. The remaining material in the test tube has a
mass of 10.27 g. What total mass of ammonia and water vapor was produced in
the reaction?
4. When a solution of barium nitrate and solution of copper (II) sulfate or mixed,
a chemical reaction produces solid barium sulfate, which sinks to the bottom, and
a solution of copper (II) nitrate. Suppose some barium nitrate is dissolved in
120.00 g of water and 8.15 g of copper (II) sulfate is dissolved in 75.00 g of water.
The solutions are poured together, and a white solid forms. After the solid is
filtered out off, it is found to have a mass of 10.76 g. The mass of the solution that
passed through the filter is 204.44 g. What mass of barium nitrate was used in
the reaction?
5. A reaction between sodium hydroxide and hydrogen chloride gas produces
sodium chloride and water. A reaction of 22.85 g of sodium hydroxide with 20.82
g of hydrogen chloride gets off 10.29 g of water. What mass of sodium chloride is
formed in the reaction?
6. An 18 g sample of element A combines completely with a 4 g sample of element
B to form the compound AB. What is the mass of the compound formed?](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F3d3c8e59-5df8-485b-a3d1-c26ab674f5c2%2F08c04969-4784-43ac-8568-96d2c9ba7c72%2Fmi7aomg_processed.png&w=3840&q=75)
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Physical changes are defined as changes that involve a change in the display but no change in composition is observed or,
Physical changes occur when the object undergoes a change that does not affect the chemical composition.
Chemical change: It involves the combination of two or more substances to form a new substance and this is called chemical reaction.
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