Chem question how do u do this? (1 Viewer)

[FlueyGuey111]

 

[tgone]

C?

 

[FlueyGuey111]

C?

ye ur right howd u do it

 

[tgone]

ye ur right howd u do it

writing down the indicators they test:

colourless [12.0-14.0] orange
colourless [8.3-10.0] pink
yellow [6.4-8.0] red
blue-violet [3.0-5.0.] red

assuming that a 'red' solution means purely red, the first two must be colourless, i.e. pH<8.3, and the other two need to be ensured as both red, i.e. pH>8.0, then pH ∈ [8.0, 8.3]

 

[FlueyGuey111]

writing down the indicators they test:

colourless [12.0-14.0] orange
colourless [8.3-10.0] pink
yellow [6.4-8.0] red
blue-violet [3.0-5.0.] red

assuming that a 'red' solution means purely red, the first two must be colourless, i.e. pH<8.3, and the other two need to be ensured as both red, i.e. pH>8.0, then pH ∈ [8.0, 8.3]

ohhhhh ty i get it

 

[someth1ng]

BTW, in real life, that's definitely not how you should use indicators. I think this is a scientifically bad question. I can argue for practically any answer here. Keep in mind that pink is often considered a light shade of red (and if you dilute a red solution, you'll get pink).

A. red+red+dark pink+colourless (adds up to red)
B. red+red+pink+colourless (adds up to red)
C. red+red+colourless+colourless (adds up to red)
D. red+yellow/red+colourless+colourless (might end up orange but wouldn't count on it)

If you have indicators mixed that mix orange/yellow with red, you might have a lot of trouble distinguishing them, and may look very similar to red. This is why pH indicator strips have four squares. It's better to just test the sample with each indicator separately.

 

[tgone]

BTW, in real life, that's definitely not how you should use indicators. I think this is a scientifically bad question. I can argue for practically any answer here. Keep in mind that pink is often considered a light shade of red (and if you dilute a red solution, you'll get pink).

A. red+red+dark pink+colourless (adds up to red)
B. red+red+pink+colourless (adds up to red)
C. red+red+colourless+colourless (adds up to red)
D. red+yellow/red+colourless+colourless (might end up orange but wouldn't count on it)

If you have indicators mixed that mix orange/yellow with red, you might have a lot of trouble distinguishing them, and may look very similar to red. This is why pH indicator strips have four squares. It's better to just test the sample with each indicator separately.

View attachment 36498

definitely agree - i just thought this was the 'intended' way of using them by this question intepreting 'red' as the indicator purely 'red' as given, I think it's a very poor question.

 

[wizzkids]

There is a so-called "Universal Indicator" that contains a mixture of thymol blue, methyl red, bromothymol blue and phenolphthalein. The aim is to make an indicator that changes colour progressively through the range pH4 to pH14. They supply a colour chart to read off the correct pH value, but it is quite subjective. Neutral pH7 is a sort-of leaf green in Universal Indicator.