Solutions and Solubility pt 1 Flashcards
What is the law of conservation of matter?
Summarizes scientific observations about matter by stating that there is not detectable change in the total quantity of matter present when matter converts from one type to another (chemical change) or changes among solid, liquid, or gaseous states (physical change)
What can be true according to the law of conservation of matter?
Matter is neither created nor destroyed (must have same number and type of atoms)
When atoms gain or lose electrons to yield ions or combine with other atoms to form molecules, what is true of their symbols?
Symbols are modified or combined to generate chemical formulas that appropriately represent these species
What does a chemical equation symbolize?
Acts as symbolism to represent both the identities and the relative quantities of substances undergoing a chemical (or physical) change
What are reactants?
Substances undergoing reaction on the left side
Where are reactants found in a chemical equation?
Left side
What are products?
The substances generated by the reaction on the right
Where are products found in a chemical equation?
Right side
Plus signs do what in a chemical equation?
Separate individual react and product formulas
The arrow does what in a chemical equation?
Separates the react and product (left and right) sides of the equation
What is the purpose of coefficients in a chemical equation?
Numbers placed immediately to the left of each formula to act as the relative numbers of reactant and product species
What is a balanced equation?
The equal numbers of atoms for each element involved in the reaction are represented on the reactant and product sides
Formula subscripts do what to a chemical equation?
Formula subscripts define and maintain the identity of the substance, therefore they cannot be changed
True or False: It is important for the charge to be balanced on both the reactant and product sides in a balanced equation
True
Write a balanced equation for the decomposition of ammonium nitrate to form molecular nitrogen, molecular oxygen, and water.
2 NH4NO3 ⟶ 2 N2 + O2 + 4 H2O
True or False: It is sometimes convenient to use fractions instead of integers as intermediate coefficients in the process of balancing a chemical equation.
True
True or False: When balance is achieved, all the equation’s coefficients may then be multiplied by a whole number to convert the fractional coefficients to integers without upsetting the atom balance.
True
True or False: It is common practice to use the smallest possible whole-number coefficients in a chemical equation
True
What are common abbreviations for the physical states of reactants and products?
s for solids, l for liquids, g for gases, and aq for substances dissolved in water (aqueous solutions)
What are solutions?
homogeneous mixtures of two or more substances
What is a solvent?
one component of a solution is present at a significantly greater concentration
What are the remaining components without the solvent called?
Solutes
What are solutes
The other components of the solution present in relatively lesser concentrations
True or False: Water is used so often as a solvent that the word solution has come to imply an aqueous solution to many people. However, almost any gas, liquid, or solid can act as a solvent.
True
What are some defining traits of solutions?
They are homogeneous; that is, after a solution is mixed, it has the same composition at all points throughout (its composition is uniform).
The components of a solution are dispersed on a molecular scale; that is, they consist of a mixture of separated molecules, atoms, and/or ions.
The dissolved solute in a solution will not settle out or separate from the solvent.
What occurs when ionic compounds dissolve in water?
the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them
True or False: Water and other polar molecules are attracted to ions
True
What is an ion-dipole attraction?
The electrostatic attraction between an ion and a molecule with a dipole
What are electrolytes?
Substances that produce ions in solutions when they dissolve
What are nonelectrolytes?
Substances that do not yield ions when dissolved
How can substances be identified as strong, weak, or non-electrolytes?
by measuring the electrical conductance of an aqueous solution containing the substance
True or False: Solutions may also conduct electricity if they contain dissolved ions, with conductivity increasing as ion concentration increases.
True
True or False: Electrolytes (such as salts) conduct electricity when dissolved in water
True
True or False: non-electrolytes (such as sugar and ethanol) do not conduct electricity when dissolved in water
True
What is the definition of a balanced equation?
chemical equation with equal numbers of atoms for each element in the reactant and product
What is the definition of a chemical equation?
symbolic representation of a chemical reaction
What is the definition of a coefficient?
number placed in front of symbols or formulas in a chemical equation to indicate their relative amount
What is the definition of a product?
substance formed by a chemical or physical change; shown on the right side of the arrow in a chemical equation
What is the definition of a reactant?
substance undergoing a chemical or physical change; shown on the left side of the arrow in a chemical equation
What does it mean to say an equation is balanced? Why is it important for an equation to be balanced?
To say you have a balanced equation means you have an equal number of total atoms on the reactant and product side of the reaction. This is important since the law of conservation has to be applied; no matter is lost throughout the reaction
Why are most solid ionic compounds electrically nonconductive, whereas aqueous solutions of ionic compounds are good conductors? Would you expect a liquid (molten) ionic compound to be electrically conductive or nonconductive? Explain
Most solid ionic compounds have neutral charge, and so there are no electrolytes able to conduct charge. Aqueous solutions of ionic compounds are good conductors because they dissociate to form ions (atoms with charge), which are good electrolytes. One would expect a liquid (molten) ionic compound to conduct electricity because the ions are free to move more in a liquid state than a solid state, and thus, able to allow electricity to flow.
What are the basic steps in balancing chemical equations?
- Change coefficients not subscripts
- Label the states of matter and other reaction conditions
- Make sure quantities and charges are balanced
What is a precipitation reaction?
Type of aqueous reaction/solution that discusses issues of solubility (if compounds are soluble or not)
If a compound is soluble, what is it considered?
Strong electrolyte
If a compound is not soluble, what is it considered?
Non-electrolyte
True or False: Soluble ionic compounds are electrolytes
True
True or False: Molecules other than acids/bases tend not to be electrolytes
True
Strong electrolytes dissociate entirely into?
Soluble ionic compounds, strong acids
Weak electrolytes dissociate entirely into?
Weak acids, weak bases
When does a precipitation reaction occur?
When two aqueous solutions are mixed to form an insoluble product
What is true of NH4+ and alkali metal ions?
They are always soluble
What is true of NO3- and CH3COO-?
They are always soluble
What is true of Cl-, Br-, and I-?
They are usually soluble, but are not soluble with Ag+, MgHg22+, Pb2+
What is true of CO32-, PO43-?
They are usually insoluble
What is another term to refer to precipitation reactions as and why?
“Exchange or metathesis reaction” because it seems as if ax + by –> ay + bx
