Chemistry Final
Avogadro's number
6.022 x 10^23
Mole
6.022 x 10^23 particles
Apart from making life difficult for beginning chemistry students, why do chemists refer to CO2 as carbon dioxide, yet use the name tin(IV) oxide to describe SnO2?
Carbon dioxide is a molecular compound - two no metals, also seen in "di" which is a molecular naming convention. Tin (IV) oxide is an ionic compound since Tin is a metal. In this one, the (IV) indicates that Tin has a charge of 4+. (The Román numeral is required when s metal can form more than one ion, the transition metals on the periodic table.)
Compound conductivity
Conductive = ionic liquid and ionic dissolved because the ions are more spread out and can flow and conduct
endothermic reaction
Energy enters the system. Indicators: a positive change in H value, system gets warmer, surroundings feel cold
Exothermic reaction
Energy exists the system. Indicators: a negative change in H value, system gets cooler, surroundings feel hot
What happens in a single replacement reaction?
In a single replacement reaction, the reactants are a metal and an aqueous ionic compound. If the lone metal is above the metal in the ionic compound on the activity series, then the lone metal will kick the other metal out of the compound. Then that metal will now be alone, and the stronger metal will take its place in the ionic compound in aqueous solution.
What combinations of elements give rise to ionic compounds and which form molecular compounds?
Ionic compounds - between metal and nonmetal (or more than one nonmetal in the case of poly atomic ions). Molecular compounds are made of only non metals.
Ionic and molecular compounds
Ionic solid: made of metal and non-metal charges that are connected in a tight lattice Molecular solid: made of only min-metals in individual "packets" of molecules that are not interconnected
Why do ionic solids have higher melting and boiling points than do most molecular solids?
Ionic solids are held in a tight lattice due to all of the positive and negative charges attracting each other. Since the ions are held so tightly, they are hard to break apart, and therefore it is hard to melt or boil then which requires spreading the particles apart. Molecular solids have lower melting and boiling points since it is easier to spread the molecules apart, since they are not (as tightly) interconnected to each other.
How many ions are formed when solid Na2SO4 dissolves? What are the ions formed? How many atoms are there in this compound? Draw it.
Na2SO4 is sodium sulfate. Three ions, two are sodium Na+ and the other is sulfate SO4 2-. There are seven atoms ... 2 sodium, 1 sulfur, and 4 oxygen.
Molar mass
The mass of one mole of a certain particle
What happens in a double replacement reaction? How do you know if the products are solid or aqueous?
The reactants in a double replacement are two ionic compounds in aqueous solution. When they react, the ions switch partners. You have to check the solubility table to see if either of them will make a precipitate (solid), or stay in aqueous solution.
molecular formula
a formula giving the number of atoms of each of the elements present in one molecule of a specific compound.
empirical formula
a formula giving the proportions of the elements present in a compound but not the actual numbers of atoms.
