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akhl

@akhl

Dazzler

Posted: 15 years ago

#141

Originally posted by: Miggi
Hello,
I am in university( first year) and I need help in Chemistry's lab.

okay we did a lab on determination of gas constant R.

and I need to report atlest 4 possible sources of systematic errors.

To give brief Intro " material used were Burette appratus which is used to measure the vol. of H2 gas, two samples of metal, HCl, erlenmeyer flask.

In this experiment we had to measure the vol of hydrogen gas when a known metal was reacted with excess HCl, strong acid. nd then we used experimental data to find gas constant R.

I hope i provided enufff info.

Plzz i need help ASAP.THnxx in advance.

Did you measure temperature and pressure also or did you assume STP or RTP?

Quote

akhl

@akhl

Dazzler

Posted: 15 years ago

#142

Originally posted by: Miggi
Hello,
I am in university( first year) and I need help in Chemistry's lab.

okay we did a lab on determination of gas constant R.

and I need to report atlest 4 possible sources of systematic errors.

To give brief Intro " material used were Burette appratus which is used to measure the vol. of H2 gas, two samples of metal, HCl, erlenmeyer flask.

In this experiment we had to measure the vol of hydrogen gas when a known metal was reacted with excess HCl, strong acid. nd then we used experimental data to find gas constant R.

I hope i provided enufff info.

Plzz i need help ASAP.THnxx in advance.

1. Deviation in the actual behavior of hydrogen gas from ideal gas behavior.
2. Backlash error.
3. inequality, if any, of balance arms of physical balance
4. Manufacturing or inbuilt defect or limitation of the instruments used.

Quote

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Sonia

@Miggi

Inactive

Posted: 15 years ago

#143

Originally posted by: akhl

1. Deviation in the actual behavior of hydrogen gas from ideal gas behavior.
2. Backlash error.
3. inequality, if any, of balance arms of physical balance
4. Manufacturing or inbuilt defect or limitation of the instruments used.

thnxx for ur help :)

Quote

Sonia

@Miggi

Inactive

Posted: 15 years ago

#144

Hey all!

i have four questions on calculus and in all of them we have to find derivatives

1) (7-xe^x)/(x+e^x)

2) f(x)= 4x^2sinxtanx

3)(x^2 +1)(x^2+2)^1/3

4) y = 4^2^x^2

I need to hand in these ques with in two hours plzz help ASAP

Thanks in advance.

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akhl

@akhl

Dazzler

Posted: 15 years ago

#145

1) y = (7-xe^x)/(x+e^x)

dy/dx = [(x+e^x)(-xe^x - e^x) + (7-xe^x)(1+e^x)]/(x+e^x)^2

= [-e^x(x+e^x)(x+1) + (7-xe^x)(1+e^x)]/(x+e^x)^2 (Answer)

2) f(x)= 4x^2sinxtanx

d/dx (f(x)) = 4x^2 d/dx (sinxtanx) + 4 d/dx (x^2) sinxtanx

= 4x^2 d/dx (sinxtanx) + 4 (2x) sinxtanx

= 4x^2 (sinx sec^2x - cosx tanx) + 8x sinx tanx

= 4x^2 sinx sec^2x - 4x^2 cosx tanx + 8x sinx tanx

= 4x^2 sinx sec^2x - 4x^2 cosx sinx/cosx + 8x sinx tanx

= 4x^2 sinx sec^2x - 4x^2 sinx + 8x sinx tanx

= 4x^2 sinx (sec^2x - 1) + 8x sinx tanx

= 4x^2 sinx tan^2x + 8x sinx tanx (Answer)

3) y = (x^2 +1)(x^2+2)^1/3

dy/dx = (x^2 + 1) (1/3)(x^2+2)^(-2/3) (2x) + (2x) (x^2+2)^1/3

= (2/3) (x) (x^2 + 1) (x^2 + 2)^-2/3 + 2x(x^2 + 2)^1/3 (Answer)

4) y = 4^2^x^2

Let u = 2^x^2

y = 4^u = e^(u ln4)

dy/du = e^(u ln4) * ln4 = 4^u ln4

dy/du = 4^2^x^2 (ln4)

u = 2^x^2 = e^(x^2 ln2)

du/dx = e^(x^2 ln2) (2x ln2)

du/dx = 2^x^2 (2x ln2)

dy/dx = dy/du * du/dx

= 4^2^x^2 (ln4) * 2^x^2 (2x ln2)

= 2x ln2 ln4 * 2^x^2 * 4^2^x^2

= 2x ln2 * 2 ln2 * 2^x^2 * 4^2^x^2

= (4x) (ln2)^2 (2^x^2) (4^2^x^2) (Answer)

Quote

akhl

@akhl

Dazzler

Posted: 15 years ago

#146

1) y = (7-xe^x)/(x+e^x)

dy/dx = [(x+e^x)(-xe^x - e^x) + (7-xe^x)(1+e^x)]/(x+e^x)^2

= [-e^x(x+e^x)(x+1) + (7-xe^x)(1+e^x)]/(x+e^x)^2 (Answer)

2) f(x)= 4x^2sinxtanx

d/dx (f(x)) = 4x^2 d/dx (sinxtanx) + 4 d/dx (x^2) sinxtanx

= 4x^2 d/dx (sinxtanx) + 4 (2x) sinxtanx

= 4x^2 (sinx sec^2x - cosx tanx) + 8x sinx tanx

= 4x^2 sinx sec^2x - 4x^2 cosx tanx + 8x sinx tanx

= 4x^2 sinx sec^2x - 4x^2 cosx sinx/cosx + 8x sinx tanx

= 4x^2 sinx sec^2x - 4x^2 sinx + 8x sinx tanx

= 4x^2 sinx (sec^2x - 1) + 8x sinx tanx

= 4x^2 sinx tan^2x + 8x sinx tanx (Answer)

3) y = (x^2 +1)(x^2+2)^1/3

dy/dx = (x^2 + 1) (1/3)(x^2+2)^(-2/3) (2x) + (2x) (x^2+2)^1/3

= (2/3) (x) (x^2 + 1) (x^2 + 2)^-2/3 + 2x(x^2 + 2)^1/3 (Answer)

4) y = 4^2^x^2

Let u = 2^x^2

y = 4^u = e^(u ln4)

dy/du = e^(u ln4) * ln4 = 4^u ln4

dy/du = 4^2^x^2 (ln4)

u = 2^x^2 = e^(x^2 ln2)

du/dx = e^(x^2 ln2) (2x ln2)

du/dx = 2^x^2 (2x ln2)

dy/dx = dy/du * du/dx

= 4^2^x^2 (ln4) * 2^x^2 (2x ln2)

= 2x ln2 ln4 * 2^x^2 * 4^2^x^2

= 2x ln2 * 2 ln2 * 2^x^2 * 4^2^x^2

= (4x) (ln2)^2 (2^x^2) (4^2^x^2) (Answer)

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akhl

@akhl

Dazzler

Posted: 15 years ago

#147

You posted your question too late. Still I answered soon after I saw your questions.

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Sonia

@Miggi

Inactive

Posted: 15 years ago

#148

Originally posted by: akhl

Thnxxx a lot i really appreciate ur help but the ans to ques1 and 2 are wrong. i dunno how but the website whr i am submitting my hw is saying tht its wrong

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akhl

@akhl

Dazzler

Posted: 15 years ago

#149

Anwers are correct. May be the website expects in some other form. As you know same expression can be written in different forms. Ok I will try to put in some other forms.

What about 3 and 4? Is the website taking those as correct?

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Sonia

@Miggi

Inactive

Posted: 15 years ago

#150

Originally posted by: akhl
Anwers are correct. May be the website expects in some other form. As you know same expression can be written in different forms. Ok I will try to put in some other forms.
What about 3 and 4? Is the website taking those as correct?

yea they r right👏

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