Chemistry Midterm Flashcards

Questions and Answers

Matter is classified as a

homogeneous mixture or as a heterogeneous mixture

substance or as a mixture of substances (correct)

homogeneous mixture, only

substance, only

Tetrachloromethane, CCl4, is classified as a

compound because the atoms of the elements are combined in a proportion that varies

compound because the atoms of the elements are combined in a fixed proportion (correct)

mixture because the atoms of the elements are combined in a fixed proportion

mixture because the atoms of the elements are combined in a proportion that varies

Which substance can be decomposed by chemical means?

tungsten

krypton

methane (correct)

antimony

Which statement describes a chemical property of the element magnesium?

Magnesium reacts with an acid. Signup and view all the answers

Solid ZnCl2 and liquid ZnCl2 have different

physical properties Signup and view all the answers

Given the balanced equation representing a reaction: CH4(g) + 2O2(g) -> 2H2O(g) + CO2(g) + heat, which statement is true about energy in this reaction?

The reaction is exothermic because it releases heat. Signup and view all the answers

In which sample is the average kinetic energy of the particles greatest?

10 mL of H2O(l) at 35C Signup and view all the answers

Which kelvin temperature is equal to 56C?

329 K Signup and view all the answers

An aqueous solution of sodium chloride is best classified as a

homogeneous mixture Signup and view all the answers

A bottle of rubbing alcohol contained both 2-propanol and water. These liquids can be separated by the process of distillation because the 2-propanol and water

have combined physically and retain their different boiling points Signup and view all the answers

A student observed the following reaction: AlCl3(aq) + 3NaOH(aq) -> Al(OH)3(s) + NaCl(aq). After products were filtered, which substance remained on the filter paper?

Al(OH)3 Signup and view all the answers

Which phase change is endothermic?

CO2(s) -> CO2(g) Signup and view all the answers

What is the total number of joules of heat energy absorbed when the temperature of 200.0 grams of water is raised from 10.0C to 40.0C?

25,080 Joules Signup and view all the answers

How many kilojoules of heat are needed to raise the temperature of 500 grams of water from 10.0C to 30.0C?

41.8 kJ Signup and view all the answers

Solid X is placed in contact with solid Y. Heat will flow spontaneously from X to Y when

X is 10C and Y is 5C Signup and view all the answers

At STP, which element has a definite shape and volume?

Ag Signup and view all the answers

Which 5.0-millimeter sample of NH3 will take the shape of and completely fill a closed 100.0-millimeter container?

NH3(g) Signup and view all the answers

How many joules of heat energy are needed to completely melt 25.0 grams of ice to water at 0C?

8,350 J Signup and view all the answers

The phase change represented by the equation I2(s) -> I2(g) is called

sublimation Signup and view all the answers

Study Notes

Classification of Matter

Matter can be classified as either a substance or a mixture of substances.
Homogeneous mixtures have uniform composition, whereas heterogeneous mixtures do not.

Tetrachloromethane

Tetrachloromethane (CCl4) is a compound with fixed proportions of elements.

Decomposition by Chemical Means

Methane is a substance that can be decomposed through chemical reactions.

Chemical Properties of Magnesium

A notable chemical property of magnesium is its reaction with acids.

Physical Properties of ZnCl2

Solid and liquid forms of zinc chloride (ZnCl2) exhibit different physical properties.

Energy in Chemical Reactions

The combustion reaction of methane is exothermic, meaning it releases heat during the process.

Average Kinetic Energy

The average kinetic energy of particles is highest in 10 mL of liquid water at 35°C compared to other samples.

Temperature Conversion

56°C is equivalent to 329 K in Kelvin.

Aqueous Solutions

An aqueous solution of sodium chloride (NaCl) is classified as a homogeneous mixture due to its uniform composition.

Distillation Process

2-propanol and water can be separated through distillation as they are mixed physically and maintain distinct boiling points.

Filtration of Reactions

In the reaction of AlCl3 with NaOH, aluminum hydroxide (Al(OH)3) remains as a solid on the filter paper after filtration.

Endothermic Phase Change

The phase change of carbon dioxide from solid to gas (sublimation) is an endothermic process.

Heat Energy Calculations

Raising the temperature of 200 grams of water from 10°C to 40°C requires 25,080 joules of heat energy.
To raise the temperature of 500 grams of water from 10°C to 30°C, 41.8 kJ of heat energy is needed.

Spontaneous Heat Flow

Heat flows spontaneously from solid X to solid Y when X is at a lower temperature than Y; e.g., from 10°C to 5°C.

Shape and Volume at STP

At standard temperature and pressure (STP), silver (Ag) has a definite shape and volume, characteristic of solids.

Behavior of Gases

Ammonia gas (NH3) takes the shape of and fills the closed container completely as it is in the gaseous state.

Heat Required for Phase Changes

To completely melt 25.0 grams of ice at 0°C to water requires 8,350 joules of heat energy.

Sublimation

The phase change described by the equation I2(s) → I2(g) is known as sublimation, where a solid transitions directly to a gas.

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Test your knowledge with these flashcards designed for the Chemistry midterm. Each card presents key concepts and classifications about matter and chemical substances. Perfect for quick revision before your exams!