CH4 Flashcards by Juwel Jacob

What do all acids contain in their formula Whats the definition of an acid

H
A substance that releases Hydrogens ions as H+ in aqueous solution,proton donor

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What’s a strong acid and weak

Releases all of its available H atoms as h+ ions and fully disassociates in aqueous solution.
Only releases a small proportion of its available H ions and partially disassociates in aq solution

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What’s a base and alkali

Proton acceptor and it neutralises an acid to form a salt
An alkali is a base that dissolves in water releasing OH- ions into solutions.

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Common bases

Metal oxides
MgO
CaO
CuO
Metal carbonates
Na2Co3
CuCo3
Alkali
NaOH
KOH
NH3

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What happens in a neutralisation reaction

H+ ions react with a base to form a salt and water. The H+ ions from acid are replaced by metal or ammonium ions from the base to make the salt

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What salt would these acids form
hyrdrochloricbacid
Sulfuric acid
Nitric acid
And Ethanoic acid

HCL-NaCl
H2SO4-Na2SO4
HNO3-Ca(NO3)2
CH3COOH-CH3COONH4

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What forms with an acid to form salt and water

Metal oxides
Metal hydroxides
Alkali

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What forms when an acids reacts with a metal

Salt and hydrogen

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What forms when acid reacts with carbonates

Salt water and carbon dioxide

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What’s the disassociation of H2SO4

H2SO4-H+ + HSO4-
Then it partially disassociates
HSO4- <==> H+ + SO4 2-
Sulfuric acid first behaves as a strong acid
HSO4 acts as a weak acid
Other strong acids behave similarly

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Why are the products of acid and alkali and acid and metal oxides the same

Both alkali and metal oxides are both bases

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How are ammonium salts formed

When avid reacts with aqueous ammonia

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What are hydrated crystals

A crystalline structure containing water

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What does anhydrous crystals mean

Crystalline form that contains no water

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What does a dot formula indicate

The amount of water oresent in a crystalline structyre

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What colour does powder go after water drives off

White but it’s very hard to get it fully white as it’s very hard to remove last traces of water by heat

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What’s a titration and what’s it used to calculate

Technique used to accurately measure the volume of one solution that reacts exactly with another solution
It’s used to-
Find conc of solution
Identify unknown chemicals
Finding purity of a substance

What’s a standard solution and what’s used to measure it

A solution of known concentration
Volumetric flask

How to prepare a standard solution

1)Solid weighed accurately
2)Then it’s dissolved in a beaker using less distilled water than needed to fill the volumetric flask to the mark
3)Solution then transferred to 250cm3 volumetric flask. Last traces of solution in beaker rinsed into flask with distilled water.
4)Flask carefully filled to the graduation line by adding distilled water a drop at a time w a pippette until the bottom of the meniscus lines exactly with the mark
5) volumetric flask inserted w a stopper n slowly inverted several times to mix thoroughly.

What would happen if flask is filled with water above graduation line ?

What would happen if flask isn’t filled with water upto graduation line?

And if flask not inverted?

Titre would be more as solution is more dilute.
Titre would be less and more concentrated
If the flask is not inverted, the solution won’t be evenly mixed. The first sample taken may be more dilute, requiring a larger titre. Later samples may be more concentrated, giving smaller titres, leading to inconsistent results

How to complete a titration

1) add measured volume of one solution to a conical flask using a Pipette
2) add other solution to a burette and record inital burette reading to nearest 0.05cm3
3) add few drops of indicator to concise flask
4) run solution in burette into solution into conical flask swirling conical swirling throughout to mix the two solutions.
Indicator will change colour at end point and this indicates volume of one Auktion that exactly reacts with the volume of the second solution
5)record final burette reading.volume of solution added from burette is titre which is calculated by subtracting initial from final
6)trial titration carried out to get estimate titre
7) then repeated accurately adding solution drop by drop until end point. Carried out ongoing until two accurate titres are concordant ( within 0.10cm3)

Why do we need concordant titres

To get accurate titres

What’s oxidation jumber

The number of electrons an atom uses to bond with any other atoms

What’s the oxidation number for uncombined elements? Like C,H,O,P?

What does have an oxidation number

Compounds and ions

what’s the oxidation number for O?

-2 -1 in peroxides(h202) +2 when bonded to F

Oxidation number for F Oxidation number for H

-1 +1 (in metal hydrides -1)

Oxidation number for group 2 elements and group 1

Group 2-+2 Group 1-+1

Oxidation number for Cl,Br,I

-1

What does the sum of the oxidation numbers equal

Total charge

Oxidation number of Sulfuric acid? H2SO4

O=-2 x 4 = -8 H=+1 x 2= +2 Total charge =0 soo 2-8=-6 to get to 0 it will be +6

Oxidation number of nitrogen in NO3-?

O=-6 Total charge=-1 Soo N=+5

What’s the modern name of NO2- And NO3- and how do yiubknow the difference between them

Nitrate (|||) and nitrite (||) as the Roman numerals are the oxidation numbers of nitrogen. One nitrogen atom and 3 oxygens is ATE one nitrogen atoms and 2 oxygens is ITE

What’s nitrate and Sulfate

NO3- SO4 ^2-

What is oxidation and reduction ?

Oxidation is loss of electrons loss of hydrogen gain of oxygen. And increase in oxidation number Reduction is gain of electrons gain of hydrogen loss of oxygen.decrease in oxidation number

2Al + 3H2SO4 —>Al2(SO4)3 (ag)+ 3H2 What’s been oxidised and reduced

Al and H got ON of 0 H in 3H2 is +1 so it’s been reduced Al in Al2 is +3 so it’s been oxidised

What’s the half ewuayions for Ca + Cl—-CaCl2 And what’s been oxidised and reduced

Ca=2+ So I’m cacl2 it’s 2+ and 2- Ca—>Ca2+ +2e- calculus donated 2 electrons so it’s the reducing agent Cl2+2e——2Cl- cl2 accepted 2 electrons it’s limiting reagent

What elements been oxidised from Cl2+MgI2—MgCl2+I2 And say what’s the limiting and reducing agent

Chlorine molecule on left hand side with 2 uncharged chlorine atoms and chlorine ion on right hand side each with a charge of -1. Cl2+ 2e- ——> 2Cl- These have gained 2 electrons so it’s reducyion,oxidising reagent On left side we have 2 iodide ions with a charge of -1 and on right hand side 2 is iodine molecules with 2 uncharged iodine atoms 2I- ——>I2 +2e- As these have donated electrons it’s oxidation,limiting reagent

What’s gets oxidised in 2Fe+3Cl2—2fecl3

Fecl3 contains Fe3+ and Cl- And Fe loses electrons and gets oxidised and chlorine gains electrons and becomes reduced 2Fe—->2Fe3+ +6e- oxidised 3Cl2+6e——>6Cl- reduced There’s 2Fe so each Fe loses 3e- 6Cl each Cl gains 1e-

What’s the oxidation numbers of zn in Zn+2HCl—-Zncl2+H2

Cl=-1 x 2 so Zn = +2 Zn = 0–> +2 oxidised H=+1 —> 0 reduced But as there’s 1Zn it increases Sbu 2 As there’s 2H each H decreases by -1 so total decrease is -2 so overall increase of Zn is +2

Why do we use a volumetric pippete than a regular one

It can measure 25cm3 to a high precision