Also our dad read the Declaration of Independence to us , and I drew 4 founding fathers ( to use in Independence Day family home evening)
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Tuesday, July 7, 2015
The 4th of July , 2015 & 2015 womens world cup
We had a fine fourth of July this year, and watched the Final of the 2015 FIFA Womens World Cup Canada the next Day. We had Waffles, with cream, blueberries , strawberries and other fruits, for Breakfast. I made a circular American flag during breakfast, with cream , and the named berries.
Also our dad read the Declaration of Independence to us , and I drew 4 founding fathers ( to use in Independence Day family home evening)
We have been going to the beach recently , and have been boogie boarding. The world cup final was between The United States of America, and Japan. We scored 4 goals in the first 16 minutes!, with 75% of them being Lloyd's hat trick ( she had one from half field, and the Japanese keeper fell down backing up to save it :) . Japan came back with 2 goals, one of them being an own goal. Then shortly after the 2nd Japanese goal the United States of America got back and scored one, after an amazing corner that the keeper saved, and then a pass and goal, right through the midst of defenders. The game Ended 5-2, and the United States of America won their 3rd title, and are now the all time best team again. The United States of America let in the least goals in the tournament , only 3.
Also our dad read the Declaration of Independence to us , and I drew 4 founding fathers ( to use in Independence Day family home evening)
Monday, July 6, 2015
AP Scores !!
My AP scores came in today. On Biology I got a 3 and on Chemistry I got a 5. I have already Explained the 5 point grading scale, with 1 being the lowest score. I passed both my AP exams, got 10 credit hours ( 3 from AP BIOL and 7 from AP CHEM ) and 1.5 general requirements ( for the College I sent my scores to, they were Biological science and 1/2 of Physical Science ). I also got credit for BIOL 100 and CHEM 105 ,& 106. I am very happy with the result, ( I liked Chemistry better than Biology , so that's that ).
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| First My Dad Called the AP College Board Services to Discover the Scores. But then I did get a College Board Account , and here are the scores online |
Wednesday, July 1, 2015
Some of Big Idea 6: Equilibrium
My AP scores are coming this Monday, the 6th, and this is going to be the last subject blog about AP Chemistry. Big Idea 6 is the biggest idea in my opinion, so I will not cover all of it, my apologies. Reactions ( which are covered in Big Idea 3 ) are reversible, they can go both ways. When the rate of each direction is equal, then the reaction is at equilibrium. With Le Chatelier's principle you can determine which way an equilibrium will shift when you add a stress. Here are some types of stress you can apply and which way the equilibrium will shift:
Add more reactant or product ( increasing the concentration of a reactant or product ): The Reaction will shift away from the added compound ( for example, if it is added reactant, then it will shift right, toward the product side, to take away the added reactant )
Take away reactant or product ( decreasing the concentration of a reactant or product ): The reaction will shift towards the depleted compound ( for example , if it is depleted reactant, then it will shift left, toward the reactant side, to restore the original amount of reactant )
Increase the pressure ( this only works with equilibrium reactions that have compounds in the gaseous state in them ) : To find which way it would shift, you count the number of moles of gas on each side of the reaction. With an increase in pressure it would shift to the side with the least moles of gas.
Decrease the pressure ( this only works with equilibrium reactions that have compounds in the gaseous state in them ) : To find which way it would shift, you count the number of moles of gas on each side of the reaction. With a decrease in pressure it would shift to the side with the most moles of gas.
Increase in Temperature ( for this stress, you need , and will be given , to know if the reaction is Exothermic or Endothermic ) : If the reaction is exothermic , you can make heat go on the product side, and act as a product ( If it is endothermic, heat goes on the reactant side, and behaves as a reactant ). So an increase of heat means an increase of either reactant ( Endothermic reactions ) or product ( Exothermic reactions ) , and means that the equilibrium will shift away from the added heat.
Decrease in Temperature ( for this stress, you need , and will be given , to know if the reaction is Exothermic or Endothermic ) : If the reaction is exothermic , you can make heat go on the product side, and act as a product ( If it is endothermic, heat goes on the reactant side, and behaves as a reactant ). So a decrease of heat means a decrease of either reactant ( Endothermic reactions ) or product ( Exothermic reactions ) , and means that the equilibrium will shift towards the depleted heat.
Remember , Exothermic means - ΔH while Endothermic means + ΔH.
You can setup an equilibrium constant expression on any reversible reaction. It looks like this :
K=[products]^coefficient
[reactants]^coefficient
Where K is the equilibrium constant, and the [ brackets] mean Molarity. Solids and liquids are not used in the expression. There are many types of K , there is Kc , Kp, Ksp, Ka & Kb. K changes with temperature , according to the following equation:
ΔG=-RTlnK , which rearranged is K=e^-ΔG/RT. An increase of temperature is an increase in K ( and therefore K and T are directly proportional ) also this can be explained on the molecular level without math. With the needed values of K and the other compound molarites you can find the concentration of a compound with unknown concentration, using the Equilibrium constant expression. Kc is the Equilibrium constant expression for concentration, Kp for pressure, Ksp the solubility product constant, Ka the Acid equilibrium constant, and Kb for bases.
You can do a lot of math with these, plenty of it Algebra. I am going to go through only 3 of them and not in to much detail. The simplest one is finding a concentration of a reactant/product with known Kc and other reactant/product concentrations. Example:
What is the concentration of NH3 in the reaction NH3+H2O(l) <=> NH4+ +OH-, If [NH4+]=4 ,[OH-]=2 , and the Kc is ( this I must tell you, is totally made up, sorry, you can look up some K's online ) 10 ?
First set up the expression:
Kc=[NH4+][OH-]
[NH3]
Remember, Liquids aren't used.
Then rearrange it ( for [NH3] ) with basic algebra:
[NH3]= Kc
[NH4+][OH-]
And finally insert the values given:
[NH3]= 10 = 10/8=1.25 M
(4)(2)
Kp uses gas pressures instead of concentration:
What is the Kp of the reaction N2+2O2<=> 2NO2 , If the pressure of the reactants and products are 3,6 and 5 atms respectively ?
set up the expression:
Kp=(PNO2)^2
( PN2)( PO2)^2
Plug in the values
Kp=5^2 = 25=0.231 ( rounded to 3 sig figs , this might not be the real Kp for the reaction )
( 3)( 6)^2 108
Ka is the equilibrium constant for acids, Big Idea 6 has more on acids and bases ( which I will not cover on this blog ), like Titrations and buffers. We are going to do a problem that requires the Quadratic equation:
What is the pH of a 0.01 M HF solution ? The Ka is 7.2*10^-4 ( now this one is the right K )
write the reaction for the dissociation of Hydrofluoric acid:
HF<=> H+ + OH-
( all aqueous )
set it up :
Ka=[H+][OH-]
[HF]
Then you do some ICE box work and get
7.2*10^-4=x^2
0.01-x
After some Algebra....
(0.01-x)(7.2*10^-4)=x^2
7.2*10^-6-7.2*10^-4x=x^2
you get it in standard quadratic form ( a+b+c, in this case a=1, b =7.2*10^-4 , and c= -7.2*10^-6 ):
x^2+7.2*10^-4x - 7.2*10^-6=0
Then you use the quadratic equation:
x=-b + (sqrt)b^2-4ac
2a
x=-7.2*10^-4+(sqrt)7.2*10^-4^2+4(7.2*10^-6)
2
We use + in this case not - .
The - and the - on 7.2*10^-6 cancel out to leave us +
And we get...... 0.00235 M , which equals the [H+]. Now to find the pH you need to take the
-log of the [H+] , which equals 2.63 and this is the pH!!
Q is the reaction quotient, with it you can determine the proportion of Products to reactants at any point in a reaction. With this and the K value you can determine if the reaction is at equilibrium or not ,and ( if it is not at equilibrium) which way it will shift and what it will favor.
If QIf Q>K, than the reaction isn't at equilibrium and will shift left, favoring the reactants.
While if Q=K , the reaction is at equilibrium.
There is a way to determine an unknown K from known K's of similar reactions, like Hess's law.
But the rules are a bit different:
If a reaction is multiplied by a number, than its K is raised to the power of that number. Example:
N2+2O2<=> 2NO2 -----> 2N2+4O2<=> 4NO2
K -----> 2K
If a reaction is flipped or reversed, than the K will become a reciprocal of its original value. Example:
N2+2O2<=> 2NO2 -----> 2NO2<=> N2+2O2
1
K -----> K
And instead of adding the K's ( when the reactions are arranged so that all things cancel exept the ones in the wanted reaction ), you multiply them together.
( remember my sources from my last AP Chemistry blog )
Add more reactant or product ( increasing the concentration of a reactant or product ): The Reaction will shift away from the added compound ( for example, if it is added reactant, then it will shift right, toward the product side, to take away the added reactant )
Take away reactant or product ( decreasing the concentration of a reactant or product ): The reaction will shift towards the depleted compound ( for example , if it is depleted reactant, then it will shift left, toward the reactant side, to restore the original amount of reactant )
Increase the pressure ( this only works with equilibrium reactions that have compounds in the gaseous state in them ) : To find which way it would shift, you count the number of moles of gas on each side of the reaction. With an increase in pressure it would shift to the side with the least moles of gas.
Decrease the pressure ( this only works with equilibrium reactions that have compounds in the gaseous state in them ) : To find which way it would shift, you count the number of moles of gas on each side of the reaction. With a decrease in pressure it would shift to the side with the most moles of gas.
Increase in Temperature ( for this stress, you need , and will be given , to know if the reaction is Exothermic or Endothermic ) : If the reaction is exothermic , you can make heat go on the product side, and act as a product ( If it is endothermic, heat goes on the reactant side, and behaves as a reactant ). So an increase of heat means an increase of either reactant ( Endothermic reactions ) or product ( Exothermic reactions ) , and means that the equilibrium will shift away from the added heat.
Decrease in Temperature ( for this stress, you need , and will be given , to know if the reaction is Exothermic or Endothermic ) : If the reaction is exothermic , you can make heat go on the product side, and act as a product ( If it is endothermic, heat goes on the reactant side, and behaves as a reactant ). So a decrease of heat means a decrease of either reactant ( Endothermic reactions ) or product ( Exothermic reactions ) , and means that the equilibrium will shift towards the depleted heat.
Remember , Exothermic means - ΔH while Endothermic means + ΔH.
You can setup an equilibrium constant expression on any reversible reaction. It looks like this :
K=[products]^coefficient
[reactants]^coefficient
Where K is the equilibrium constant, and the [ brackets] mean Molarity. Solids and liquids are not used in the expression. There are many types of K , there is Kc , Kp, Ksp, Ka & Kb. K changes with temperature , according to the following equation:
ΔG=-RTlnK , which rearranged is K=e^-ΔG/RT. An increase of temperature is an increase in K ( and therefore K and T are directly proportional ) also this can be explained on the molecular level without math. With the needed values of K and the other compound molarites you can find the concentration of a compound with unknown concentration, using the Equilibrium constant expression. Kc is the Equilibrium constant expression for concentration, Kp for pressure, Ksp the solubility product constant, Ka the Acid equilibrium constant, and Kb for bases.
You can do a lot of math with these, plenty of it Algebra. I am going to go through only 3 of them and not in to much detail. The simplest one is finding a concentration of a reactant/product with known Kc and other reactant/product concentrations. Example:
What is the concentration of NH3 in the reaction NH3+H2O(l) <=> NH4+ +OH-, If [NH4+]=4 ,[OH-]=2 , and the Kc is ( this I must tell you, is totally made up, sorry, you can look up some K's online ) 10 ?
First set up the expression:
Kc=[NH4+][OH-]
[NH3]
Remember, Liquids aren't used.
Then rearrange it ( for [NH3] ) with basic algebra:
[NH3]= Kc
[NH4+][OH-]
And finally insert the values given:
[NH3]= 10 = 10/8=1.25 M
(4)(2)
Kp uses gas pressures instead of concentration:
What is the Kp of the reaction N2+2O2<=> 2NO2 , If the pressure of the reactants and products are 3,6 and 5 atms respectively ?
set up the expression:
Kp=(PNO2)^2
( PN2)( PO2)^2
Plug in the values
Kp=5^2 = 25=0.231 ( rounded to 3 sig figs , this might not be the real Kp for the reaction )
( 3)( 6)^2 108
Ka is the equilibrium constant for acids, Big Idea 6 has more on acids and bases ( which I will not cover on this blog ), like Titrations and buffers. We are going to do a problem that requires the Quadratic equation:
What is the pH of a 0.01 M HF solution ? The Ka is 7.2*10^-4 ( now this one is the right K )
write the reaction for the dissociation of Hydrofluoric acid:
HF<=> H+ + OH-
( all aqueous )
set it up :
Ka=[H+][OH-]
[HF]
Then you do some ICE box work and get
7.2*10^-4=x^2
0.01-x
After some Algebra....
(0.01-x)(7.2*10^-4)=x^2
7.2*10^-6-7.2*10^-4x=x^2
you get it in standard quadratic form ( a+b+c, in this case a=1, b =7.2*10^-4 , and c= -7.2*10^-6 ):
x^2+7.2*10^-4x - 7.2*10^-6=0
Then you use the quadratic equation:
x=-b + (sqrt)b^2-4ac
2a
x=-7.2*10^-4+(sqrt)7.2*10^-4^2+4(7.2*10^-6)
2
We use + in this case not - .
The - and the - on 7.2*10^-6 cancel out to leave us +
And we get...... 0.00235 M , which equals the [H+]. Now to find the pH you need to take the
-log of the [H+] , which equals 2.63 and this is the pH!!
Q is the reaction quotient, with it you can determine the proportion of Products to reactants at any point in a reaction. With this and the K value you can determine if the reaction is at equilibrium or not ,and ( if it is not at equilibrium) which way it will shift and what it will favor.
If Q
While if Q=K , the reaction is at equilibrium.
There is a way to determine an unknown K from known K's of similar reactions, like Hess's law.
But the rules are a bit different:
If a reaction is multiplied by a number, than its K is raised to the power of that number. Example:
N2+2O2<=> 2NO2 -----> 2N2+4O2<=> 4NO2
K -----> 2K
If a reaction is flipped or reversed, than the K will become a reciprocal of its original value. Example:
N2+2O2<=> 2NO2 -----> 2NO2<=> N2+2O2
1
K -----> K
And instead of adding the K's ( when the reactions are arranged so that all things cancel exept the ones in the wanted reaction ), you multiply them together.
( remember my sources from my last AP Chemistry blog )
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