Exam 1

Iron reacts with hydrochloric acid to produce iron(II) chloride and hydrogen gas. Fe(s) + 2 HCl(aq) → FeCl2(aq) + H2(g) What mass of H2(g) is produced from the reaction of 5.2 g Fe(s) with excess hydrochloric acid?

0.19 g

What are the values for x and y, respectively, in CaxHyPO4?

1 and 1

Which of the following statements is/are postulates of Dalton's atomic theory?

1. Elements are tiny particles called atoms. 2. No atomic changes into another element in an ordinary chemical reaction. 3. Compounds are formed when two or more atoms combine. CORRECT -->1, 2, and 3

What mass of oxygen will react with 2.64 g of magnesium? 2Mg(s) + O2(g) → MgO(s)

1.74 g

What is the mass of 0.71 mol Na?

16 g

If 16.4 g of oxygen gas react with excess hydrogen, what mass of water is produced? 2H2(g) + O2(g) → 2H2O(g)

18.5 g

The boiling point of ammonia is -33 degrees Celsius. What is the temperature in kelvin?

239.9 K

What mass of oxygen is present in 10.0 grams of potassium nitrate (KNO3)?

4.75 g

How many protons, neutrons, and electrons are in a silver atom with a mass number of 108?

47 protons, 61 neutrons, 47 electrons

How many significant figures are in the following mass: 0.00047800 kg?

5

Avogadro's Number/Constant

6.022 x 10 ^23

Express 0.00720 in exponential notation.

7.20 × 10-3

A mass of 4.00 g of H2(g) reacts with 2.00 g of O2(g). If 1.94 g of H2O(l) is collected, what is the percent yield of the reaction? 2H2(g) + O2(g) → 2H2O(l)

86 %

F-20, a radioactive isotope of fluorine, has...

9 protons, 11 neutrons, and 9 electrons.

Molecular Formula

A molecular substance is often represented by this, where the number of atoms in each element is represented by a subscript written after the symbol of the element (H2O)

Heterogeneous Mixture

A solid, liquid, or gaseous mixture that has components whose proportions vary throughout the sample.

Homogeneous Mixture

A solid, liquid, or gaseous mixture that has the same proportions of its components throughout any given sample.

Postulates Definition

A thing suggested or assumed as true as the basis for reasoning, discussion, or belief

Give the molecular formulas of ethyl alcohol, CH3CH2OH

Add up the atoms of each element and use the sums as the subscripts for the element. C: 1+1=2 H: 3+2+1=6 O: 1, so... C2H6O4

What is the correct name for Al2O3?

Aluminum oxide

Ionic Compounds

Always contains both cations (positively charged particles) and anions (negatively charged particles). They are held together by strong electrical forces between oppositely charged ions (Na+ and Cl-) and these forces are called ionic bonds.

Nonmetal atoms form negative ions when gaining electrons called...

Anions

How to find the number of protons, neutrons, and electrons of an atom and ion

Atom- Protons are always = to atomic number Neutrons are the difference between the atomic number and the mass number In an atom, the # of protons and electrons are the same Ion- Only difference is how you find the electrons, which is the # of protons - the charge

Identify the halogen from period 4.

Br (Bromine)

A molecule is found to contain 47.35% by mass C, 10.60% by mass H, and 42.05% by mass O. What is the empirical formula for this molecule?

C3H8O2

Polyethylene is a polymer consisting of only carbon and hydrogen. If 2.300 g of the polymer is burned in oxygen it produces 2.955 g H2O and 7.217 g CO2. What is the empirical formula of polyethylene?

CH2

Metal atoms typically lose electrons to form positively charged ions called...

Cations

J.J. Thomson determined that electrons are small, negatively charged particles by...

Deflecting cathode rays with electric and magnetic fields.

Percent Composition of a Formula (citing the mass percents of the elements present)

For example: in a 100-g sample of water, there are 11.19 g of hydrogen and 88.81 g of oxygen. Hence the two percentages of the elements are... 11.19g H/100.00g X 100%= 11.19% H (and then do the same for oxygen)

Which Term best describes rocks, such as granite or marble?

Heterogeneous Mixture

Periods on the periodic table

Horizontal Rows The atomic numbers increase from left to right. The periods are numbered 1 through 7 on the left-hand side of the table. Elements that are in the same period have chemical properties that are not all that similar.

Identify the ions and their charges in KH2PO4.

K+, H2PO4−

How to convert a temperature in Fahrenheit/Celsius to Kelvin (K) and vice versa?

Kelvin Temp: T(K) = t(oC) + 273.15 Fahrenheit Temp: t(oF) = 1.8 x t(oC) + 32

Groups/families on the periodic table

Members of the families (vertical columns) in the periodic table have similar properties. Numbered 1-18 Alkali metals, alkali earth metals, halogens and noble gases

Ionic Compounds are either...

Metals or Nonmetals

Molarity

Molarity (M)= moles of a solute/liters of solution

Acids

Must start with an "H"

Identify the ions and their charges in Na2SO4.

Na+, SO42−

All atoms of the same element have the same number of ____.

Protons

What is the correct formula for sulfur dichloride?

SCl2

How to find the number of protons, neutrons, and electrons of an isotope

The # of protons does NOT equal the number of electrons always. To find the # of neutrons of a given isotope with the actual number given (F-20) subtract 9 (atomic #) from 20, which =11 neutrons.

When an ionic solid dissolves in water...

The cations and anions separate from each other.

Stoichiometry

The study of mass relations in chemistry.

Balanced Equations

There are the same number of atoms of a given element on both sides.

What are significant figures?

There are three rules on determining how many significant figures are in a number: Non-zero digits are always significant. Any zeros between two significant digits are significant. A final zero or trailing zeros in the decimal portion ONLY are significant.

Molecule

Two or more atoms that combine with one another to form an uncharged molecule.

Ions

When an atom gains or loses electrons, these charged particles are formed.

Nuclear Symbol

Z= Protons+ A= Protons+ plus Neutrons Electrons= Protons+ minus charge

How many protons, neutrons and electrons are there in this ion: ^45 21 SC +3?

Z=21 Protons; A=n+p; 45=n+21; n=24 Electrons= e=21-(+3)=18

Which of the following samples contains the largest number of atoms?

a) 2.0 moles of H3PO4 b) 3.0 moles of H2SO3 CORRECT--> c) 4.0 moles of HNO3 d) 6.0 moles of HClO e) 8.0 moles of HBr

Aluminum reacts in air with oxygen to form aluminum oxide. Which of the reactions below is correct and properly balanced?

a) Al(s) + O(g) → AlO(s) b) 2Al(s) + O2(g) → 2AlO(s) c) 3Al(s) + O2(g) → Al3O2(s) d) 4Al(s) + O2(g) → 2Al2O(s) CORRECT--> e) 4Al(s) + 3O2(g) → 2Al2O3(s)

Which atom is most likely to form an ion with a +2 charge?

a) Scandium CORRECT --> b) Calcium c) Aluminum d) Oxygen e) Fluorine

All of the following statements are false EXCEPT...

a) Tin (Sn) is a homogeneous mixture of sulfur (S) and nitrogen (N) b) Table salt is a homogeneous mixture of sodium metal and chlorine gas CORRECT--> c)The air trapped in a bicycle tire is a homogeneous mixture d) Sugar dissolves completely in water to give a heterogeneous mixture e) Water (H2O) is a homogeneous mixture containing hydrogen and oxygen

Rank the subatomic particles from least to greatest mass.

electrons < protons < neutrons

Mole (n) to Gram Conversions

mass=molar mass X n

The boiling point of liquid oxygen is 90.0 K. What is the boiling point in Fahrenheit?

−297.8°F