New Standard: A.S. 91161 Carry out quantitative analysis

This standard is an internally assessed standard and will involve carrying out an acid-base titration along with chemical calculations involving Moles, Concentration, Volume: n = c x V (V = n ÷ c, c = n ÷ V )

In order to carry out this internal accurately with the aim of achieving at least a merit you will need to be able to carry out an accurate titration-so here goes.....

Watch the 2 videos below to check out how to carry out the titration and then how to go about answering calculations:



Calculations video....




To go along with the above video (from jamesmungall.co.uk) are the written calculations-as set out below:

Titration of Sodium Carbonate against Hydrochloric Acid: ·
2.606g of Anhydrous Na2CO3 was prepared with 250ml of distilled water to make a solution of Sodium Carbonate
· A 25ml aliquot of this solution was titrated against HCL
 · Methyl Orange was used as the indicator which changes colour when the Sodium Carbonate is neutralised and turned into Sodium Chloride as per the reaction:Na2Co3+2HCL---------->2NaCl+C02+H2O
 · 18.7ml of HCL was required to neutralise the reaction  

· WHAT IS THE CONCENTRATION OF THE ACID?

  · M(Na2CO3) = 106 gmol-1

 n (Na2CO3) = m / M = 2.606 / 106 = 0.0246 Mol 

This is the amount of moles in 250ml…we are using aliquots of 25ml  

so the amount of moles in 25ml is 0.0246 / 10 = 0.00246 mol 

  n (HCl) = moles of Sodium Carbonate titred x 2 as the ratio is 1:2* *from the equation:

 Na2CO3 + 2HCl à 2NaCl + Co2 + H20 Mol

 ratio:   1 : 2 

 Therefore Moles of HCl = Moles of Na2Co3 x 2 = 0.00246 x 2 = 0.00492  

Therefore the Concentration of HCl required to neutralise the Na2CO3 in this titration is found by using the following equation:  

Concentration (HCl) = moles (HCl) / volume (HCl)

 C = n / v 0.00492 / 0.0187 = 0.263 Mol/litre

Information Sheet NCEA Level 2 Chemistry Course 2012

Here is the general course information for 2012's Level 2 Chemistry:

ACHIEVEMENT STANDARDS:three internal (10 credits) and 3 external (13 credits)

	Achievement Standards
AS Code	Title	No. of credits	Mode	Type of assessment	Duration	Date assessed	Prov. topic order
A.S.91161	Chemistry 2.1 Carry out qualitative analysis	4	Internal	Practical	2 weeks	Start term 2	2
A.S.91162	Chemistry 2.2Carry out procedures to identify ions present in solution	3	Internal	Practical	2 weeks	Middle term 2	3
A.S.91164	Chemistry 2.4 Demonstrate understanding of bonding, structure, properties and energy changes	5	External	National exam	9 weeks	November	1
A.S.91165	Chemistry 2.5 Demonstrate understanding of the properties of selected organic compounds	4	External	National exam	7 weeks	November	5
A.S.91166	Chemistry 2.6 Demonstrate understanding of chemical reactivity	4	External	National exam	8 weeks	November	4
A.S.91167	Chemistry 2.7 Demonstrate understanding of oxidation–reduction	4	Internal	Practical	2 weeks	End term 3	6

NCEA Level 2 Chemistry @ Gisborne BOys' High School, 2012

Here is the newly aligned Level 2 Chemistry standards for 2012:

2012 Level 2 Chemistry Standards Matrix
AS91161 2.1Carry out quantitative analysis.4 credits Internal	AS91162 2.2Carry out procedures to identify ions present in solution.3 credits Internal	AS91164 2.4Demonstrate understanding of bonding, structure, properties and energy changes.5 credits External	AS91165 2.5Demonstrate understanding of the properties of selected organic compounds.4 credits External	AS91166 2.6Demonstrate understanding of chemical reactivity.4 credits External	AS91167 2.7Demonstrate understanding of oxidation–reduction.3 credits Internal

YEAR 10 CAMP ON THE WAIOEKA, DECEMBER 2010

The camp ran between December 6th and December 9th 2010 and involved one overnight camp / bivvy along the banks of the Waioeka River between Koranga Forks Hut and Wairata and two nights camping on Redpath's Farm at Wairata.

The overnight camp out was in the middle of a tramp from Moanui Valley along the Koranga and down the Waoieka to Wairata. Some groups, with prior planning and foresight, managed to get as far as Nikau Flats Hut which meant no more river crossings on the last day's tramp. The weather gods played ball with nice sunny weather and low levels for the numerous river crossings along the tramp. This, however, meant that the Waioeka was a little bony for the kayaking and rafting the next day. To use and abuse a quote from some of my paddling acquaintances: 'it was low and (not really) doable!', but we got down through Nutcracker and Corkscrew along with the rest of the river, albeit it with the occasional boat walk! The last morning dawned bright and sunny which was a great opportunity to dry out tents form some of the showers the day before, and even more importantly do the abseiling off the bridge in the sun! Below is a slide show of some of the photos I took on the camp:



Thanks, in no particular order, for such a successful camp must go to the following: the Redpath's for the use of the campsite, the GBHS year 10 Boys on the camp, the GBHS staff who ran/supervised the camp and activities, and the other staff and helpers..

PERIODIC TABLE

This is the start, middle and end of trying to understand chemistry and how and why elements react:

• remember group numbers and valence shell electrons!!

There are a lot of elements here and first impressions maybe that trying to remmber the elements in order up to the first 20 is too difficult....wrong!! This is where mnemonics come in!


Hopata, -  He - Like - Beer, - Bottled - Cold, - Not - Over - Frothy, - Nelly -(the) - Naughty - Might - Although - Silly - Person, - She - Climbs - Around - Kinky - Caves.


-Standing for:
Hopata = Hydrogen  
He = Helium
Like = Lithium
Beer = Beryllium
Bottled = Boron
Cold = Carbon
Not = Nitrogen
Over = Oxygen
Frothy = Fluorine
Nelly = Neon
the Naughty = Sodium
Might = Magnesium
Although = Aluminium
Silly = Silicon
Person = Phosphorous
She = Sulfur
Climbs = Chlorine
Around = Argon
Kinky = Potassium
Caves = Calcium


Using a mnemonic like this wil hopefully help with remebering the first 20 elements at least. You could even maybe com eup with one of your own!!


Here is another one for more elements...

11 PY CHEMISTRY REVISION..

Lewis Dot Diagrams continued...

For now just a quick post: CLICK HERE TO TRY WRITING LEWIS DOT DIAGRAMS FOR SOME COVALENT COMPOUNDS

YEAR 11PY CHEMISTRY REVISION

LEWIS DOT DIAGRAMS....

The basic starting point is understanding electron configuration of the elements and realising that we are only concerned with the outer shell of electrons as these electrons are the ones involved in bonding. 

REMEMBER this is the valence shell and all elements in the same group have the same valency and the same Lewis Dot Diagram configuration!


1. Draw electron dot diagrams for elements for just the outer shell. The outer shell can contain 8 electrons-the OCTET RULE.
2. Electrons need to be drawn on the four sides of the Symbol on their own first
3. After you complete the four sides start to double up the electrons so they are in pairs. It doesn't matter where you start!

Lewis Dot Diagrams for elements

The next post / updated post will continue with Lewis Dot diagrams and focus on bonds between elements.....


In the meantime check out this site for an interactive slide show on Lewis Dot Diagrams of Covalent Bonds