×
Log in to StudySoup
Get Full Access to UH - Chem 1301 - Study Guide
Join StudySoup for FREE
Get Full Access to UH - Chem 1301 - Study Guide

Already have an account? Login here
×
Reset your password

UH / Chemistry / CHEM 1301 / What is the law of constant composition?

What is the law of constant composition?

What is the law of constant composition?

Description

School: University of Houston
Department: Chemistry
Course: Foundations of Chemistry
Professor: Roman czernuszewicz
Term: Fall 2015
Tags: Chemistry, exam, study, neutron, proton, nucleus, atom, element, compound, Binary, balance, equations, scientific, and method
Cost: 50
Name: CHEM 1301 Exam 1 Study Guide
Description: This study guide is a compilation of Chapter 1-6 notes. If you already have those individually you'll be good but if you don't have the notes you should download this study guide. -Key vocabulary words -Examples -list of key things to know before the test Good luck on the exam!
Uploaded: 09/25/2016
11 Pages 12 Views 11 Unlocks
Reviews

(Rating: )


Jankinsrora (Rating: )



CHEM 1301 Exam 1 Study Guide


What is the law of constant composition?



From “Introductory Chemistry” by Zumdahl and Decoste

Things to MAKE SURE YOU KNOW before the test: 

1. How to balance equations

2. First 36 elements, specifically which are metals and which are noble gases 3. How to determine significant figures

4. Basic conversions

5. How to identify the number or protons, neutrons, and electrons in an atom Scientific Method: 1) What is the problem? What have you observed?  Qualitative (physical traits) vs Quantitative (numerical numbers)

2) Hypothesis: What is the possible explanation for this?

3) Experiment and gather information to test the hypothesis

Theory: set of tested hypotheses, possible explanation, and interpretation A law tells what happens, a theory is an attempt to explain why it happens Chapter 2  


What is a mass number?



Measurement: a number and a unit

Scientific Notation: expresses a number as a product of a number between 1 and 10 and the  appropriate power of 10

Ex: 9.3 ????(# 1-10) x 102 ???? (appropriate power of 10)

Units 

Volume: 1 dm3= 1 liter Length: meter

Mass: kilogram Volume: liters Don't forget about the age old question of agata kowalewska
If you want to learn more check out quasi-independent variable

SIGNIFICANT FIGURES ???? non-zeros are ALWAYS significant types of zeros Leading Zeros: zeroes that precede non-zero digits (Ex: 0.0025)

*NEVER count as significant


What is a neutron?



Captive Zeroes: zeroes BETWEEN non-zero digits (Ex: 1.008)

*ALWAYS count

Trailing Zeroes: zeroes at the right end of a number (Ex: 100 vs 100.) *they only count if there’s a decimal point

Exact numbers: numbers determined by calculations rather than measuring devices

*have an unlimited number of significant figures

ROUNDING OFF

Ex: 4.348 is 4.3 NOT 4.35 or 4.4  

*use only the 1st number to the right of the last significant figures

BACK TO SIGNIFICANT FIGURES We also discuss several other topics like business inteliggence

Multiplication or Division

*significant figures will be the measurement with smallest number of figures Ex: 4.56 x 1.4= 6.384 ???? 6.4

Addition and Subtraction

*significant figures will be the measurement with the smallest number of decimal places Ex: 12.11 + 18.0 + 1.013= 31.123 ???? 31.1

PROBLEM SOLVING AND DIMENSIONS

Equivalence Statement: measurements using different units that stand for the exact same  distance, amount, etc. Don't forget about the age old question of the devil made me do it sauerkids

 (2.54 cm/ 1in) = (1 in/2.54 cm) 

Conversion Factor: ratios of the two parts of the equivalence statement Ex: 2.85 cm x (1 in/2.54cm)= (2.85 in/2.54 cm)= 1.12 in  

Ex: MULTIPLE STEP PROBLEM ???? 26.2 mi= ?km

Miles ???? yards ???? meters ???? kilometers

26.2 mi x (1760 yd/1mi) x (1 mi/ 1.094 yd) x (1 km/ 103 m)= 42.1 km Temperature Conversions: An approach to Problem Solving

Farenheit OF Celcius OC Kelvin- K 273 K= freezing 373 K= boilingWe also discuss several other topics like which of the following pairs has the stronger acid listed first?

Ex: Ice Water Boiling Water

Symbol Temp  

OF 32 OC 0 K 273

Symbol Temp OF 212 OC 100 K 373

Converting between the Kelvin and Celcius Scales

CELCIUS TO KELVIN

OC + 273= temp in K

Ex: 70OC= ?K

?K= 273 + 70.= 343 K

70OC= 343 K

KELVIN TO CELCIUS

K- 273=OC

FARENHEIT TO CELCIUS

*requires two adjustments  

1) For the different size units 2) For the different zero points Note: 180OF= 100OC

Step 1: (180./100.)OF= (100./100.)OC or 1.80OF= 1.00OC If you want to learn more check out factors of 4050

Step 2: OF= 1.80( OC) + 32 ???? +32, accounts for the difference of zero points CELCIUS TO FARENHEIT

Ex: 28OC= ?OF

Temp F= 1.80( OC) +32 OC = ((OF)- 32)  = 1.80(28) +32 1.80  =50. +32= 82

 =28OC= 82OF

Density

Density= (Mass/Volume)

CALCULATING DENSITY

EX:

Liquid ???? 23.50 mL and 35.062 g

(Mass/volume)= (35.062g/25.50mL)= 1.492 g/mL or 1.492 g/cm3 *because 1 mL=1 cm3 DENSITY OF PEOPLE

*The more muscle and less fat on a person, the more dense they are

*Volume can be found through the displacement of water when submerging an object in  water

Platinum Density= 21.4 g/cm3 Silver Density= 10.5 g/cm3 Ex: Medallion purchased= 55.64g (mass)

75.2 mL of water in graduated cylinder + medallion= 77.8 mL

77.8 mL – 75.2 mL= 2.6 mL (volume)

Density= (55.64g/2.6mL)= 21 g/mL or 21 g/cm3 

Solution: Medallion is Platinum

Chapter 3  

Physical Properties: visuals like color, odor, volume, shape, state

Chemical Properties: ability to change substance (ex: from wood to ash, from sugar to  alcohol)

Physical Change: change that does NOT affect molecular structure

Chemical Change: change that affects molecular structure

Element: fundamental substance

Compounds: binding of multiple elements

Mixture: mixture of compounds to make new product/ substance (ex: wine, wood) Pure Substance: either all same elements or compounds (ex: water)

Homogenous Mixture (Solution): mix substances but keep same properties (ex: salt and water)

Heterogeneous Mixture: contains regions with different properties from other regions  (ex: sand and water separate)

Chapter 4

Law of Constant Composition: a given compound always has the same composition,  regardless of where it comes from

Ex: carbon dioxide is always 2.7g of oxygen per 1g of carbon

Dalton’s Atomic Theory

1. “Elements are made of tiny particles called atoms”

2. “All atoms of a given element are identical”

*Later corrected by Dalton to (#2): “All atoms of the same element contain the same  number of protons and electrons, but atoms of a given element may have different numbers  of neutrons”

3. “The atoms of a given element are different from those of any other element”

4. “Atoms of one element can combine with atoms of other elements to form compounds. A  given compound always has the same relative numbers and types of atoms.”

5. “Atoms are indivisible in chemical processes. That is, atoms are not created or destroyed  IN CHEMICAL REACTIONS. A chemical reaction simply changes the way the atoms are  grouped together.”

Compound: distinct substance composed of two or more elements

Rules for Writing Formulas 

1. Each atom present is represented by its element symbol

2. The number of each type of atom is indicated by a subscript written to the right of the  element symbol.

3. When only one atom of a given type is present, the subscript 1 is not written Ex: (one atom of sulfur), SO3, (3 atoms of oxygen)

Atoms are made up of subatomic parts called electrons as well as protons, the positively  charged particles

Neutron: a neutral particle, slightly larger than a proton

Chemical Formula: expresses the type of atoms and the number of each type of each  molecule of a given compound or unit

Isotopes: atoms with the same number of protons but different number of neutrons Atomic Number: number of protons in a nucleus

Mass Number: sum of the number of neutrons and protons in a nucleus Groups: elements with similar chemical properties, lined vertically

Alkali Metals: Alkali Earth Metals: Halogens: Noble Gases: Group1 Group 2 Group 7 Group 8 *Most of the elements are metals

Physical Properties of Metals 

1. Efficient conducting of heat and electricity

2. Malleability (they can be hammered into tiny sheets)

3. Ductility (they can be pulled into wires)

4. A lustrous (shiny) appearance  

Non-metals: small number of elements at upper right corner of table

Metalloids: elements are near stair step line area, mixture of metals and nonmetal  properties

Diatomic Molecules: molecules made up of two atoms

*like oxygen (02) or Nitrogen (N2)

Allotropes: different forms of a given element

Ion: a charged entity, a neutral atom- one or more electrons

Cation: a positive ion made when one or more electrons are lost from a neutral atom Anion: negatively charged ion, when atom gains extra electron

Ions are NEVER formed by a changing number of protons

Metals ALWAYS make positive ions 

Nonmetals ALWAYS make negative ions 

Most traditional metals make cations

“Substance that contain ions can conduct an electric current only if the ions can move” THUS substance cannot be solid, must be melted to conduct electricity Ionic Compounds: substance containing ions

“Chemical compound MUST have a net charge of zero”

Chapter 5

NAMING COMPOUNDS

Two Types of Binary Compounds:

1. Compounds that contain a metal and non-metal

2. Compounds that contain two non-metals

Naming Compounds that are metal AND non-metal (Types 1 and 2) 

Binary Ionic Compound: contain a positive ion (cation) and a negative ion (anion) -Cation is always written before the anion

Type 1 Compounds: The metal present forms only one type of cation Ex: Na+, Ca2+, Cs+, Al3+ *These will NEVER change, no Na2+, or Al+, or Cs2+

Type 2 Compounds: The metal present can form two (or more) cations that have different  charges

Ex: Cr can form Cr2+ and Cr3+, Cu can form Cu+ and Cu2+

Rules for Naming Type 1 Binary Compounds: 

1. In the name, cation is always first, anion always second

2. A simple cation (obtained from a single atom), gets its name from its element. Ex: Na+ is called sodium in compounds that have Na+

3. A simple anion (obtained from a single atom), is names by taking the first part of the  element name, the root, and adding –ide.

Ex: Cl- ion would be chloride

-The charges of elements are not written when in compound form but when the elements  are alone, individuals, then the charges are written Ex: Na+ and Cl- vs NaCl

-Group 1 and 2 metals are ALWAYS Type 1

Type 2 Compounds: Finding Which Charge Is Used In the Compound 

-the elements joined together must equal to a net charge of 0, thus the charge of the cation  will be that that cancels out the charge of the anion and gives us zero

Ex: FeCl3, contains one Fe3+ ion and three Cl- ions (3) + (-3) = 0

Roman numbers can be used to give you the charge of the ion ex: Fe (III) is Fe3+ Rules for Naming Type 2 Ionic Compounds: 

1. Cation always comes first in name, anion comes second

2. Because the cation can assume more than one charge, the charge is specified by roman  numerals in parentheses

-Transitioning Metals are ALMOST always Type 2

-Metals that form only one cation do not need a Roman numeral

-Group 1 elements form 1+ ions, Group 2 forms 2+ ions, Group 3 forms 3+ions Naming Binary Compounds That Contain Only Nonmetals (Type III): 1. The first element in the formula is named first, and the full element name is used. 2. The second element is named though it were an anion (even if it’s not) 3. Prefixes are used to denote the numbers of atoms present like di (2), tri (3) 4. The prefix mono- is never used for naming the first element

Ex: CO is called carbon monoxide, not monocarbon monoxide

NAMING COMPOUNDS THAT CONTAIN POLYATOMIC IONS

Ex: NH4NO3- , Ammonium Nitrate

Polyatomic Ions: charged entities composed of several atoms bound together

Oxyanions: atom of a given element, in a polyatomic ion, that has a different number of  oxygen atoms

-When there are two oxyanions, the name of the one with the smallest number or oxygen  atoms ends in –ite and the one with the largest number of oxygen atoms ends in –ate

Ex: SO32- is sulfite and So42- is sulfate

-When more than two oxyanions make up a series, hypo- (less than) and per- (more than)  are used as prefixes to name the members of the series with the fewest and the most  oxygen atoms

Ex: ClO- Hypochlorite

 ClO2- Chlorite

 ClO3- Chlorate

 ClO4- Perchlorate

Note* when a metal is present that forms more than one cation, a Roman numeral is  required to show the cation charge  

NAMING ACIDS

Acids: 1. A substance that when dissolved in water, produces (H+) ions (protons) 2. A molecule with one or more H+ ions attached to an anion

-most known for having a sour taste (Ex: lemons, citrus fruits)

Rules for Naming Acids:

1. If the anion does not contain oxygen, the acid will contain the prefix –hydro, and the  suffix –ic, attached to the root of the element

Ex: HCl (Hydrogen Chloride) dissolved in water is Hydrochloric Acid

2. When the anion contains oxygen, the acid name is formed from the root name of the  central element of the anion (or the anion itself), with a suffix of –ic or –ous. When the  anion name ends in –ate, the suffix –ic is used.

Ex: Acid Anion Name

 H2SO4 SO42- Sulfuric Acid

 HC2H3O2 C2H3O2 Acetic Acid

When the anion name ends in –ite, the suffix is used in the acid name  H2SO3 SO32-(sulfite) Sulfurous Acid

 HNO2 NO2-(nitrite) Nitrous Acid

WRITING FORMULAS FROM NAMES

*Tip: Learn the names of common acids and ionic compounds which will help with finding  the names or formulas for other compounds

Practice: 

Problem: Potassium Hydroxide

Solution: KOH *K has 1+ charge and OH has a 1- charge

Problem: Nitric Acid

Solution: HNO3 *note: this is a common acid, memorize it  

Problem: Lead (IV) Oxide

Solution: PbO2 *note: Pb has a charge of 4+ and O has a charge of 2- Chapter 6

SIGNS OF CHEMICAL REACTIONS

Most chemical reaction signals are visual, however, some may be slight differences like  temperature.

Some Chemical Reaction Signals: 

1. Color change

2. Solid forms

3. Bubbles form

4. Heat and/or flame is produced, or heat is absorbed

CHEMICAL EQUATIONS

-Chemical change ALWAYS involves atoms being rearranged from their original groups ????This is called a Chemical Reaction  

Chemical Equation: used to represent a chemical reaction by placing the reactants (chemicals present before the reaction) on the left and the products to the right of a yield  arrow (which points to what is produced)

Example: methane oxygen carbon dioxide water  CH4 + O2 ???? CO2 + H2O

 Reactants Products  

-In a chemical reaction, atoms are neither created nor destroyed, so all atoms presented in  the reactants MUST be part of the products

Balancing the Chemical Equation: both sides of the equation must have the same number of  each type of atom

Example: CH4 + O2 ???? CO2 + H2O is not balanced  But CH4 + O2 + O2 ???? CO2 + H2O + H2O is

 Final Answer: CH4 + 2O2 ???? CO2 + 2H2O

-Physical states are typically written in equations

Symbol State 

(s) Solid

(l) liquid

(g) gas

(aq) aqueous (dissolved in water)

Example: Potassium Water Hydrogen Pottasium Hydroxide   K (s) + H2O (l) ???? H2 (g) + KOH (aq)

BALANCING CHEMICAL EQUATIONS

-Main focus of chemical reactions and balancing equations is that atoms are conserved  

Experimental Observation: used by chemists to identify the identity if reactants and  products in a reaction

“The identities (formulas) of the compounds must never be changed in balancing a chemical  equation” aka “subscripts cannot be changed, nor can atoms be added to or subtracted from a  formula”

-A chemical reaction can be represented by an infinite amount of balanced equations but the BEST  balanced equation is the one where the smallest, whole numbers are used

Coefficients: the whole numbers placed in front of a formula to help balance an equation HOW TO WRITE AND BALANCE EQUATIONS

1. “Read the description of the chemical reaction. What are the reactants, the products,  and their states? Write the appropriate formulas. 

2. Write the unbalanced equation that summarizes the information from step 1. 3. Balance the equation by inspection, starting with the most complicated molecule.  Determine which coefficients are necessary  

4. Check to see that the coefficients used give the same number of each type of atom on  both sides of the arrow.”

Examples from the book: 

Example #1: K (s) + H2O (l) ???? H2 (g) + KOH (aq)

 2K (s) + 2H2O (l) ???? H2 (g) + 2KOH (aq)

 4 H atoms 4 H atoms

 2 O atoms 2 O atoms

Example #2: NH3 (g) + O2 (g) ???? NO (g) + H2O (g)

 2NH3 (g) + (5/2)O2 (g) ???? 2NO (g) + 3H2O (g)  x2 x2 x2 x2

 4NH3 (g) + 5O2 (g) ???? 4NO (g) + 6H2O (g)

 6 H atoms 6 H atoms

 4 N atoms 4 N atoms

 5 O atoms 5 O atoms

Page Expired
5off
It looks like your free minutes have expired! Lucky for you we have all the content you need, just sign up here