CHEM AND BIO HELP AND TIPS HERE

[nid404]

srry but i don't get it ! ....can someone explain to me y doctors take urine sample from pregnant ladies ?

HCG(Human chorionic Gonadotrophin) is present in a pregnant woman's urine...they take the urine sample to test for HCG.

[holtadit]

Okies people.

 Why WOULDN'T you use Universal Indicator in a titration experiment. Instead why WOULD you use methyl orange ?

[nid404]

While titrating, you can't use Universal indicator because it changes its colour gradually, gives diff colors for diff pH. You won't know when the reaction is complete...

While methyl orange or phenolphthalein are used instead because they give a sudden color change. It is better to for us to see the end point

[holtadit]

While titrating, you can't use Universal indicator because it changes its colour gradually, gives diff colors for diff pH. You won't know when the reaction is complete...

While methyl orange or phenolphthalein are used instead because they give a sudden color change. It is better to for us to see the end point

Ahhhhh.... Thanks nid. My lack of practical experience worries me. Next year I am gonna kill the teacher if we dont do proper experiments.

Kef halak ana akh means how are you my brother

[nid404]

Ahhhhh.... Thanks nid. My lack of practical experience worries me. Next year I am gonna kill the teacher if we dont do proper experiments.

Kef halak ana akh means how are you my brother

i know kef halak

ana bikhair (i knw i spelt it wrong but i knw ) Ahmadullilah (i know this is spelt wrong too )

[holtadit]

Mumtaaz ! Means excellent.


Au Revoir  ! (Can you guess what this means )

 

[nid404]

thts french dodo !

You know more arabic than you know hindi....laanat hain !

[Cool guy]

hey nid??? explain why antibiotics kill bacteria but not
viruses and describe the medicinal use of antibiotics for the
treatment of bacterial infection

[nid404]

hey nid??? explain why antibiotics kill bacteria but not
viruses and describe the medicinal use of antibiotics for the
treatment of bacterial infection

What antibiotics do is they prevent formation of bacterial cell wall, thus leading to their death
Antibiotics target only bacterial function and structure and so have no effect on virus'

[holtadit]

20 cm^3 of 1 mol/dm^3 of NaOH was titrated with a certain amount of H2SO4 of 1 mol/dm^3

The H2SO4 was added in portions. Each consecutive portion caused the temperature to rise (initial starting temp. was 25 degress):

Addition of 5 cm3      Addition of  15 cm3        Addition of  25 cm3                35 cm3
1st portion                   2nd                              3rd                               4th
27 degrees                   31                                 32                                30   


The experiment is repeated with 20 cm^3 of 0.5 mol/dm^3 of NaOH and H2SO4 of 0.5 mol/dm^3

Suggest what volume of H2SO4 would produce the highest temp. ?

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No MS available, but I think its 50 cm3

[nid404]

Just by looking it gives me 12.5cm3

I'll work it out still...10-15min

[holtadit]

Just by looking it gives me 12.5cm3

I'll work it out still...10-15min

There are fewer moles of acid in the NEW experiment. Doesnt that mean a greater volumes is needed ?

[nid404]

my bad.....50 it is

[holtadit]

Is the products side correct ? Dichlorobutane...

[nid404]

2 H molecules from the alkane cannot be substituted in one go.

You only change the position of the Cl, not the number. This process happens in stages.