MIDTERM REVIEW Please get out: Paper, pencil, calculator and all chemistry knowledge 

Would freezing liquid mercury be considered a physical or chemical change? Qualitative measurement

physical

Would dissolving sodium chloride in water be considered a physical or chemical change? Error

physical

What are the two categories of pure substances? Good precision, poor accuracy

Elements and compounds

How can an element be further separated How can an element be further separated? By ordinary physical means; By ordinary chemical means; Or it cannot be further separated by ordinary physical or chemical means. kilogram

Cannot be separated by ordinary physical or chemical means

As what type of matter would you classify vinegar (acetic acid in water)? SI= m^3, non-SI= L

Homogeneous mixture

At one point in the school year, our room was a comfortable 85°F At one point in the school year, our room was a comfortable 85°F. Is this observation qualitative or quantitative? 2.5 x 10^3

quantitative

A group of measurements that closely agree with one another but are far from the “true” value are said to be… 5.9 x 10^-6

precise

How many sig figs are in the following measurement: 0.0390060 40,600

6 sf

Object A has a mass of 15. 2 g and a volume of 3. 6 mL Object A has a mass of 15.2 g and a volume of 3.6 mL. Object B has a volume of 4.1 mL and a mass of 16.8 g. Which will sink first in water? 0.073

Object A (4.22g/mL vs. B= 4.10g/mL

You are in the lab and need to mix hydrochloric acid and water You are in the lab and need to mix hydrochloric acid and water. In what order should you do this? 3.0 x 10^6

Pour acid into water

Which subatomic particle has a mass so small that it is considered negligible when finding mass number? 8 sfs

electron

An unknown element has 38 protons, 36 electrons, and 50 neutrons An unknown element has 38 protons, 36 electrons, and 50 neutrons. Identify the element. 4 sfs

Always use protons for identity Strontium (*Sr2+)

Isotopes occur when atoms of the same element have different mass numbers. Therefore, an isotope has the same # of ______, but a different # of ______. 2 sfs

Same = protons Different = neutrons

An atom has an atomic # of 31 and a mass # of 70 An atom has an atomic # of 31 and a mass # of 70. How many protons, electrons, and neutrons does the atom have? 5 sfs

Protons = 31 Electrons = 31 Neutrons = 39

What family has an electron configuration that ends in p5? 1500 cg

Halogens

What is the Noble Gas configuration for Selenium (Se)? 21 daL

[Ar]4s23d104p4

How many electrons can be held in each energy level (n=1-4) of the atom? 98 dm

n = 1  2e- (s) n = 2  8e- (s, p) n = 3  18e- (s, p, d) n = 4  32e- (s, p, d, f)

Do metals generally form cations or anions? 348 K

cations

Give the group and period trend for atomic radius. 52.63

Decreases across a period, increases down a column.

What type of elements tend to form covalent/molecular bonds?

2 nonmetals

According to VSEPR theory, what is the molecular geometry of the compound silicon tetrachloride?

Tetrahedral

What type of bond is likely to form between two atoms with the same electronegativity value?

A nonpolar covalent bond

When comparing single, double and triple covalent bonds, a single covalent bond has the (shortest/longest) bond length and the (strongest/weakest) bond strength.

Longest – bond length weakest – bond strength Single Covalent Bond Longest – bond length weakest – bond strength

What is the correct name for Mn(C2H3O2)4?

Manganese (IV) acetate

What is the correct name for C3H8?

Tricarbon octahydride

What is the correct formula for ammonium sulfite?

(NH4)2SO3

A compound contains 47. 0% K, 14. 5% C, and 38. 5 % O A compound contains 47.0% K, 14.5% C, and 38.5 % O. Its molecular weight is 166.22 g/mol. What is its molecular formula?

K2C2O4

If aqueous solutions of strontium chloride and sodium sulfate are mixed together, will a precipitate form?

Yes, strontium sulfate is insoluble (s)

What do we call the ions that appear in identical forms among both the reactants and products of a complete ionic equation that are not written in the net ionic equation?

Spectator ions

Classify and balance the reaction below: __ K3PO4 + __CdCl2  __KCl + __Cd3(PO4)2

Double Replacement 2 K3PO4 + 3 CdCl2  6 KCl + 1 Cd3(PO4)2

In the balanced combustion reaction of ethane (C2H6), oxygen has the stoichiometric coefficient of ____.

Seven 2 C2H6 + 7 O2  4 CO2 + 3 H2O

What is the molar mass of magnesium nitrate?

Mg(NO3)2 = 148.33 g/mol

How many moles of pyridine (C5H5N) are contained in 3.13g of pyridine?

0.0396 moles

In an experiment, a 0. 33 mole sample of N2 reacts completely In an experiment, a 0.33 mole sample of N2 reacts completely. What is the mass of Mg consumed in the reaction? 3 Mg + N2  Mg3N2

24.07 g Mg

Mg (s) + 2 H2O (l)  Mg(OH)2 (s) + H2 (g) In an experiment, the reaction of 4.73g of Mg with 1.83g of H2O actually produced 0.095g of H2. What is the percent yield of this reaction? Mg (s) + 2 H2O (l)  Mg(OH)2 (s) + H2 (g)

92.23% yield