Chemistry ch 4 chemical reactions anc chemical quantities

EXAM 2 SUPER IMPORTANT

the green house effect

the greenhouse gass in the atmosphere allow sunlight to enter the atmosphere and warms earth’s surface

what do the greenhouse gasses prevent?

some of the heat generated by the sunlight from escaping

what determines the earths average temperature?

the balance between incoming and outgoing energy from the sun

what does sunlight pass through to warm the earth?

the atmosphere

what happens to some of the heat radiated from earths surface?

it is trapped by greenhouse gases

what rise in atmospheric temperature have scientists measured? since when?

0.7 degrees celcius since 1860

chemical reaction:

a process in which one or more substances are converted into one or more different ones

what do chemical reactions invole?

chemical changes in matter resulting in new chemical substances

combustion reaction ******

a particular type of chemical reaction in which a substance combines with oxygen to form one or more oxygen-containing compounds

what does a combustion reaction emit?

heat and light energy

chemcial reactions involve rearrangement and exchange of:

atoms to produce new molecules and their bonds in the reactants.

states of reactions : (g)

gas

States of reactants: (l)

liquid

states of reactants: (s)

solid

states of reactants: (aq)

aqueous solution, where the solute is dissolved in water.

what is not transmitted during a chemical reaction?

elements

reactants to:

products

combustion of methane:

methan gas burns to produce carbon dioxide gas and gaseous water

whenever something burns it combines with?

O2 (g) oxygen gas (CH4 (g) + O2 (g) → CO2 (g) + H2O(g)) oxygen (O2)

to correct problems in combustion of methane we must:

balance the equation by changing the coefficients, not the sunscrips

to show that a reaction obeys the law of conservation of mass, the equation must be:

balanced

why do we adjust the number of molecules in cumbustion of methane?

so there are equal numbers of atoms of each element on both sides of the arrow

reaction stoichiometry

the balanced chemical equations for the fossil-fuel combustion reactions provide the exact relationship between the amount of fossil fuels burned and the amount of carbon dioxide

reaction stochiometry equation example

2 C8H18(l) + 25 O2 (g) 16 CO2 (g) + 18 H2O(g);16 CO2 molecules are produced for every 2 molecules of octane burned!!

what is a quantities in chemical reactions?

the amount of every substance used and made in chemical reaction is related to the amounts of all the other substances in the reaction

what is another quantity in chemical reactions?

law of conservation of mass

what is an additional quantities in chemical reactions?

balancing equations by balancing atoms

stochiometry:

the study of the numerical relationship between chemical quantities in a chemical reaction

what do the coffeicents in a chemical reaction specify?

the relative amounts in moles of each of the substances involved in the reaction as represented in the balanced equation.

mole to mole conversions

we use the ration from the balanced chemical equation to convert between moles of reactants and products.

what does the ration of the coefficients acts as a conversion factor between?

the moles of reactants and products in a chemical reaction.

what does the ratio act as a conversion factor between in a mole to mole conversions?

the amount in moles of the reactant and the amount in moles of the product

what is the conversion factor molar mass factoring between?

the mass of the given amount in moles

what do we use coeefiecents as the conversion factor between?

the reactant and the amount of moles of the product, and the the molar mass as the conversion factor to get the mass of a substance produced

conceptual connection:

Coefficients in a balanced chemical equation allow us to relate the amount of reactants to the amount of products, indicating the proportions in which they react and form.

liminiting reactant:

The substance that is consumed entirely in a chemical reaction, thereby determining the maximum amount of product that can be formed.

theoratical yeild

The maximum amount of product that can be obtained from a chemical reaction, calculated based on the stoichiometry of the balanced equation and the amounts of limiting reactants.

percent yield:

The ratio of the actual yield of a product obtained from a chemical reaction to the theoretical yield, expressed as a percentage. It measures the efficiency of the reaction.

in a chemical reaction for reactions with multiple reactants, what Is likey?

the reactants will be completely used before the others

what happens when a reactant is use dup Ina chemical reaction?

the reaction stops and no more product is made

what is it called when the reactant limits the amount of product?

liminiting reactant

reactants not completely consumed are called:

excess reactants

what is the amount of product that can be made from the limiting reactant called?

theoretical yield

the theoretical yeild is the amount of product that can be:

made in the chemical reaction based on the amount of limiting reactant

the actual yeild is:

the amount of product actually produced by a chemical reaction

the percent yield is calculated with :

actual yeild

——————— x 100%

theoretical yeild

when finding the limiting reactant and theoretical yeild we must:

first convert grams to moles

combustion reactants:

are characterized by the reaction of a substance with O₂ to form one or more oxygen-containing compounds, often including water

what do combustion reactions always entail?

the reaction of a hydrocarbon with oxygen to produce carbon dioxide in water

alkali metals reactions:

reactions of alkali metals with none matals are vigorous> alkali metals also react with water to form the dissolved alkali metals ion, the hydroxide ion and the hydrogen gas

halogen reactions

the halogens all react with many metals to form metal halides, hydrogen halides and they react with each other to form interhalogen compounds