Acids as Food Additives, Naturally Occuring Bases and Acidic Salts (1 Viewer)

[serge]

Syllabus Questions for the Acidic Environment

1. Explain the use of acids as food additives...

(Has it got something to do with our tongues
only sensing 3 types of taste?)

2. Examples of naturally occuring acids and bases

I know stomach acid is HCl, are there any bases in the body?
Who knows any easy to remember bases somewhere in nature?

3. A range of salts that form neutral, basic or acidic solutions?


thanks in advance

 

[Dreamerish*~]

1. Explain the use of acids as food additives.

Acids are used as food additives for two reasons:

1. To provide a sour taste
2. To act as a preservative, as the growth of microorganisms is not favoured by an acidic environment.

Common additives include acetic acid in vinegar, and citric acid in drinks.

2. Examples of naturally occuring acids and bases.

Yes, HCl is naturally present in the stomach. Citric acid (C₆H₈O₇) is present in citrus fruits such as lemons, acetic acid (CH₃COOH) is present in vinegar, and carbonic acid (H₂CO₃) in rain.

Bases? Ammonia is a naturally occuring base - it's in bird poo. Sodium hydrogen carbonate (or sodium bicarbonate) is baking soda.

3. A range of salts that form neutral, basic or acidic solutions.

Don't quite understand the question. Form from these solutions under what reactions?

 

[serge]

3. A range of salts that form neutral, basic or acidic solutions.

Don't quite understand the question. Form from these solutions under what reactions?

thanks dreamerish (somehow i knew you'd answer these questions)

the syllabus isnt any more specific than that but i think they mean form acidic, basic or neutral solutions if you dissolve the salts in water...

PS- I read from the syllabus that citric acid is 2-hydroxypropane-1,2,3 tricarboxylic acid

Isnt hydroxy -OH?

therefore if 1 citric acid dissociates it will form 3 H+ and 1 OH-?

 

[Dreamerish*~]

thanks dreamerish (somehow i knew you'd answer these questions)

the syllabus isnt any more specific than that but i think they mean form acidic, basic or neutral solutions if you dissolve the salts in water...

PS- I read from the syllabus that citric acid is 2-hydroxypropane-1,2,3 tricarboxylic acid

Isnt hydroxy -OH?

therefore if 1 citric acid dissociates it will form 3 H+ and 1 OH-?

Haha, yeah, I have no life. (Come sig this too, Arvin?)

Hmm, well then. A salt is an ionic compound, which means it must have a metal in it. Metallic compounds do not usually form acidic solutions, so I really have no idea. I'm sorry.

Yes, citric acid is triprotic. It has an OH group, but that OH group doesn't come off in solution.

 

[punk_tartan]

that dot point concerning "a range of form acidic, basic or neutral soloutions" what i thought this was refering to was the fact that
a strong acid + a Strong base = a neurtal salt ( eg NaOH + HCl gives NaCl which is neutral

a weak acid + a strong base gives a basic salt ie NH3 and HCl gives NH4Cl which is acidic because when this dissociates , the NH4 will form back into NH4OH leaving excess Hydronium ions...
i dont think ive explained that very welll but i hope it hwpls. if it confuses you more ask someone else lol

 

[Dreamerish*~]

that dot point concerning "a range of form acidic, basic or neutral soloutions" what i thought this was refering to was the fact that
a strong acid + a Strong base = a neurtal salt ( eg NaOH + HCl gives NaCl which is neutral

a weak acid + a strong base gives a basic salt ie NH3 and HCl gives NH4Cl which is acidic because when this dissociates , the NH4 will form back into NH4OH leaving excess Hydronium ions...
i dont think ive explained that very welll but i hope it hwpls. if it confuses you more ask someone else lol

That's exactly what I thought.

But they just wouldn't phrase it like that. That's just weird.

 

[punk_tartan]

this is the Nsw boarf of studies were talking about... i dont think they were very good at english

 

[Dreamerish*~]

this is the Nsw boarf of studies were talking about... i dont think they were very good at english

*Mutters* Why not just get rid of English altogether...

 

[Captain pi]

1. Explain the use of acids as food additives.

Acids are used as food additives for two reasons:

1. To provide a sour taste
2. To act as a preservative, as the growth of microorganisms is not favoured by an acidic environment.

Common additives include acetic acid in vinegar, and citric acid in drinks.

Congratulations on your benefactor status! (Sorry if it is old news)

As to your post,
Is this sufficient for the purposes of HSC? What if they ask a six mark "Assess the use of acids as food additives"?

 

[Dreamerish*~]

Congratulations on your benefactor status! (Sorry if it is old news)

As to your post,
Is this sufficient for the purposes of HSC? What if they ask a six mark "Assess the use of acids as food additives"?

Thank you very much. No, it's actually this morning's news.

Gosh, wouldn't we be screwed if that was in the exam. I really doubt they would go too deep into that point. The main points are flavouring and preservation of food, back it up by the characteristic sour taste of acids and the difficulty of bacteria reproducing in an acidic environment. I wrote a whole load of crap for a past paper question and my tutor told me that all I needed to say was those two points, and I would have had the 2 marks.

 

[Haku]

acid used in those fish can thingy to neutralise the fish smell from ammonia and stuff produced by dead finish.

best use ever

 

[wanton-wonton]

Yes, citric acid is triprotic. It has an OH group, but that OH group doesn't come off in solution.

It's a COOH group, and I always thought it does come off in solutions......

 

[sambo_rambo]

Its just the 3H+ bits. Then you're left with 3 lots of COO-

 

[SmileyCam]

that dot point concerning "a range of form acidic, basic or neutral soloutions" what i thought this was refering to was the fact that
a strong acid + a Strong base = a neurtal salt ( eg NaOH + HCl gives NaCl which is neutral

a weak acid + a strong base gives a basic salt ie NH3 and HCl gives NH4Cl which is acidic because when this dissociates , the NH4 will form back into NH4OH leaving excess Hydronium ions...
i dont think ive explained that very welll but i hope it hwpls. if it confuses you more ask someone else lol

From what I understand, thats pretty right,

if a salt is fromed by:
a weak acid + a strong base it gives a basic salt eg, sodium acetate
a strong acid + a weak base it gives a acidic salt eg, ammonium chloride
a weak acid + a weak base it gives a neutral salt eg, ammonium acetate
a strong acid + a strong base it gives a neutral salt eg, sodium chloride

this is because when the salt dissovles the ions, eg, ammonium and chlorine ionise in the following reversible reactions at different rates
NH4+ + H2O <--> NH4OH + H+ (this favours the right)
Cl- + H2O <--> HCl + OH- (this favours the left)
so there would be a lot more H+ therefore it's an acidic salt

 

[Haku]

that is an early post

what is an acetate?

and can u please give an equation formula for each of the four?

 

[Abtari]

2. Examples of naturally occuring acids and bases.

Bases? Ammonia is a naturally occuring base - it's in bird poo. Sodium hydrogen carbonate (or sodium bicarbonate) is baking soda.

how is baking soda a natural source?
wouldn't it be better off to say sodium bicarbonate IS naturally occurring base but not give the example u mentioned, of baking soda? hmmm perhaps, sodium bicarbonate in the blood maybe?

 

[SmileyCam]

acetate (like acetic acid) CH3COO-

sodium acetate: CH3COONa
ammonium chloride: NH4Cl
ammonium acetate: CH3COONH4
sodium chloride: NaCl

 

[SmileyCam]

how is baking soda a natural source?
wouldn't it be better off to say sodium bicarbonate IS naturally occurring base but not give the example u mentioned, of baking soda? hmmm perhaps, sodium bicarbonate in the blood maybe?

perhaps soda ash, should be better?

 

[Abtari]

wot is soda ash? never heard of it lol

um, yeah, the reason i said sodium bicarbonate was cos its part of the buffer solution in the blood, technically it is amphiprotic but u could still get away with mentioning it as a naturally occurring base. could.

 

[SmileyCam]

oh, well actually soda ash is Na2CO3, its not actually a base, it's a basic salt

NaHCO3 would be a great one, it's only a buffer solution as just HCO3-, a solution of NaHCO3(aq) would be basic tho