Determine the Acid Concentration of a Household Acid.
What is an acid?
A molecule that is a proton donor.
What are the types of acids?
Brønsted-Lowry acid
Lewis acid
Must contain hydrogen
A proton donor
Electron pair reciever
Molecule does not require a hydrogen atom
What are common household acids?
Yogurt
Citrus fruits
apples
Milk?
Batteries
The electrolyte is the acid
malic acid
lactic acid
lactic acid
Chemical properties
Will not use in experiment, as the liquid is too viscous to dilute correctly.
Could use in experiment, as it is abundant and wont spoil if unrefridgerated.
Unlikely to use, as the milk will need to be refrigerated for several hours before the experiment.
Will not use, as it is too difficult to safely remove the electrolyte
Unlikely to use, as it is difficult to juice an apple
Citric acid
Citric acid
Highly water soluble due to polarity from functional groups
One hydroxyl group
3 carboxyl groups
Citric acid is stronger than malic acid, as there are more carboxyl groups
C6H8O7
lactic acid
Water soluble
carboxylic acid group
hydroxy group
CH3CH(OH)COOH
malic acid
HIghly water soluble due to polarity from functional groups
One hydroxy group
two carboxylic groups
Hydroxyl groups also participates in hydrogen bonding
Carbonyl is a hydrogen bond acceptor and donor
C4H6O5
Method & Materials
Variables
The concentration of the standard solution
Indicator options
Methyl orange
Phenopthalein
Bromothymol blue
Commonly used for carbonic acid/carbon dioxide presence in a liquids
Normally used for substances that have a pH near 7 (weak acids)
Yellow at pH 6 and below, changes to blue at roughly pH 7.6 and above. Goes green between pH 6.6 and 7. In titration prac, aiming for green as you will get closer to neutral
Used for stronger acidic solutions and is effective betweeen pH 3.1 - 4.4
Red at pHs roughly 2 and below, yellow at PHs 4 and above. Orange between 3.1 & 4.4
Univeral indicator
Effective for all pH ranges
Effective for solutions between pH 8.3 - 10.0
Phenol Red
Effective between pHs 6.4 - 8.0
Yellow at pH 6.4 and below, deep pink at pH 8 and above. Lighter, almost creamy pink between pH 6.4 and 8
click to edit
Effecive range between pHs 6.0 and 7.6
Will use as it has the lowest range of pHs that the desired pH lies within
Base using
Base options
Strong
Weak
ammonia
trimethyl ammonia
NaOH
KOH
ammonia
weak as the nitrogen atom has a free electon pair that readily accepts a proton (H+ ion).
when dissolved in water, ammonia aquires hydrogen ions from the water.
Due to it being a weak base, getting a more accurate pH will be easier.
Their ionic bond means when dissolved in an aqueous solution, the two oppositly charged atoms break the bond and become free-floating ions. The negatively charged ions are proton acceptors.
Materials
1x 100ml volumetric flask
1x ceramic tile
1x volumetric pipette filler
1x 200mL beaker
1x 20ml volumetric pipette
1x burette
1x conical flask
1x clamp stand