TEN: Chapter 3- Chemical Change Flashcards
Physical property
Properties that describe the physical appearance and composition of a substance
Change to a substance in which the composition of the substance stays the same
Ex:
Malleability, crystal shape, streak test, state, ductility, conductivity, solubility, mass, toxicity, volume, temp, color
Chemical property
Properties that describe the reactivity of a substance
Change to a substance that always results in the formation of a different substance or substances
Five clues to a chemical reaction occurrence
A new substance has been created, bubbles or a gas released, changing temp, colour change, a precipitate forms
Exothermic reaction
A chemical reaction that releases energy, usually in the form of heat or light or electricity
Endothermic reaction
Chemical reaction that absorbs energy
Biochemical reactions
Maybe either endothermic or exothermic. Characteristics bio chemical reaction include reactions that are essential to life. Two important bio chemical reactions are photosynthesis and cellular respiration
Photosynthesis
Means putting together with light
Photo-light
Synthesis-putting together
It is a chemical process in which carbon dioxide from the air and water from the soil, in the presence of light and energy that is glucose and oxygen
Cellular respiration
Breakdown of glucose small molecules to release chemical energy that a cell can use
Physical change
A change that doesn’t result in the change of the substance but how it looks
Chemical change
A change that results in a completely different substance than the first
Difference between a chemical and physical change
It’s can be in different states and look different if it is a physical change, whereas I chemical change results in a new substance
The conservation of mass: Antoine Lavoisier
The total mass of reactants must equal the total mass of all the products
A chemical reaction must contain the following
Correct formula for each reactant and product, physical state of each reactant and product, must be balanced
Balancing guidelines
Start with the element that is the longest subscript, keep the polyatomic ion’s together if they appear on both sides of the reaction, leave elements until last, multiply to increase the number of Atoms or groups, write water as HOH in reactions that have the hydroxide ion in them, move back-and-forth as you balance
Types of reactions: five
Formation, single decomposition, single replacement, double replacement, combustion and other
Formation reactions
It shows the formation of a compound: element plus element equals compound
Simple decomposition reactions
It is the opposite of formation:compound equals element plus element
Single replacement reaction’s
They involve replacement of an element with an atom from a compact this will produce a new element and a new compound: if the element is a metal, it will exchange places with the positive ion in the compound by attaching
If the element is a nonmetal, it will exchange places with a negative ion by attaching itself to the positive ion
Element plus compound equals new element plus new compound
Note: polyatomic ion’s generally remain intact in a chemical reaction, water is generally written as HOH, if the reaction occurs in an aqueous environment use your solubility chart to predict the solubility of their ionic products of a single replacement reaction in water
Double replacement reactions
Involves the exchange of ions between compounds. Usually the reactants are two compounds and the products or two compounds.
Compound plus compound equals new compound plus new compound
The ionic charges of each of the compounds get switched with one another so the compound starts with a positive and ends with a negative
These reactions can be further subdivided into neutralization and precipitation reactions
Neutralization and precipitation reactions
Neutralization:Usually produce water as one of the products and the other is often assault of some kind
Precipitation: Produce one low solubility compound and one high solubility compound from 2 reactant compounds that are usually high solubility
Combustion reactions
Element or compound plus oxygen equals some common oxides
Common oxides include: carbon dioxide, nitrogen oxide, sulphur dioxide, water
(CO2 NO2 SO2 H2O)
In this reaction a compound or element reacts with oxygen to form the most common oxides.
The most common oxides are:
If metal is combusted – use the ionic formula for that metal oxide
If hydrogen is combusted – H20 gas is produced
If nitrogen is combusted – NO2 gas is produced
If sulphur is combusted – S02 gas is produced
Almost always balance oxygen last
Mole
Quantity that chemists use to measure elements and compounds
Symbol: mil
1 mol: 6.02 times 10 to the power of 23
Molar mass
Mass of one mole of a substance
It is the mass number in the upper right corner of an element
G/mol
Ionic
Metal plus no metal
Positive plus negative
Molecular
Nonmetal plus non-mental
Negative plus negative
Acid
Has hydrogen in it
Determining the number of moles
Number of miles equals mass divided by molar mass (N= m divided by M
You first figure out the molar mass
You want it in grams not kilograms
Kilograms times 1000 to get grams
Determining the mass from given number of moles
You look at the table to see the prefix used
First figure out the molar mass
You multiply the powered number by the given mass of moles in the equation and then cross multiply that with the molar mass to give you the mass in grams
