Conservation of Mass and Properties of Matter

Flashcards testing knowledge on physical and chemical properties of matter, phase changes, the Law of Conservation of Mass in closed systems, balanced chemical equations, types of mixtures, and physical separation techniques.

What is matter defined as in the lecture notes?

Matter is anything that has mass and takes up space, and it is made of tiny particles called atoms.

What physical properties of matter are listed in the recap?

Appearance, melting point, boiling point, density, solubility, texture, color (luster), hardness, malleability, ductility, and electrical conductivity.

What three chemical properties of matter are identified in the recap?

Combustibility, reactivity to water, and corrosiveness.

Which phase transitions represent direct changes between a solid and a gas in this diagram?

Sublimation (solid changing directly to gas) and Deposition (gas changing directly to solid).

How are the properties and phase changes of solids, liquids, and gases explained at a microscopic level?

They are explained by the motion and spacing of particles, as all matter is made of atoms in constant random motion.

Why do phase changes not alter the identity of a material?

Phase changes are reversible physical transformations during which the total amount of matter and mass remains constant.

What does the Law of Conservation of Mass state?

Mass is neither created nor destroyed by chemical reactions or physical transformations. The mass of reactants in a chemical reaction equals the mass of the products.

In the combustion of methane shown here, how is mass conserved during the chemical reaction?

The reactant mass of methane ($16\,\text{g}$) plus oxygen ($2 \times 32\,\text{g} = 64\,\text{g}$) equals $80\,\text{g}$, which equals the product mass of carbon dioxide ($44\,\text{g}$) plus water ($2 \times 18\,\text{g} = 36\,\text{g}$), totaling $80\,\text{g}$.

What is the defining characteristic of a closed system regarding mass and energy?

A closed system allows energy to be exchanged with its surroundings, but matter cannot enter or leave.

Why does total mass remain constant during any change in a closed system?

Because the total number and type of atoms stay the same, even if the atoms are rearranged to form new substances.

What balanced chemical equation is depicted for the formation of liquid water from hydrogen and oxygen gases?

$$2\text{H}_{2(g)} + \text{O}_{2(g)} \rightarrow 2\text{H}_2\text{O}_{(l)}$$

What do the coefficients in front of chemical symbols in a chemical equation represent?

Coefficients represent the number of molecules involved in the reaction.

What three specific examples of conservation of mass are provided in the text?

1. Water freezing into ice. 2. A baking soda and vinegar reaction in a closed container. 3. Mixing salt and sand.

What is a mixture?

A mixture is a material composed of two or more substances physically combined that retain their separate compositions and can be separated by physical processes.

How does a suspension differ from a solution?

A solution is a homogeneous mixture consisting of a solute dissolved in a solvent, whereas a suspension is a heterogeneous mixture with larger, visible solid particles that do not dissolve and may settle out over time.

What is a colloid, and what examples are given in the text?

A colloid is a mixture consisting of microscopic particles suspended in another medium. Examples include milk, smoke, gelatin, ink, and hand lotion.

Which physical separation method relies on pouring off a top layer of liquid based on differences in density?

Decanting.

How do filtration and sifting differ when physically separating materials?

Filtration uses a filter to separate solid particles from liquids, whereas sifting uses a sieve to separate larger solid particles from smaller ones.

What are the separation techniques of chromatography and centrifugation used for?

Chromatography separates mixture components based on different rates of movement through a medium (e.g., ink pigments), while centrifugation spins mixtures at high speeds to separate components based on density (e.g., blood components).

Why does the conservation of mass matter in practical applications?

It helps scientists predict and control chemical reactions, ensures accurate experimental measurements, and connects to real-life processes like cooking, burning fuel, and recycling.