Question

@ In my aby I used a technique to measure H concentration. If I measure the concentration in sample to be 1.592 (+0.008) mm, what is the pH of the sain? What will the absoluk unitaunty be? Expresswanswer meanswer wit correct of sig Figs.

Answer 1

Addition or subtraction The absolute uncertainty of a number calculated by addition or subtraction is obtained by using the absolute uncertainties of numbers used in the calculations as follows Abs. Uncert. Answer = (Abs. Uncert.value }} +(Abs. Uncert.value2) + ... Multiplication and Division The relative uncertainties are used for all numbers in the calculation Rel. Uncertamwer = M(Rel. Uncertvate } + (Rel. Uncert.vahez )' + ... For Logarithms For natural log In(x+ Ar) = In(x)+ 41 For logio log(x+Ar) = log(x) + 203 1 Ax

pH = -log[H] [H+] = (1.592 + 0.008) mM= (1.592 + 0.008) * 10-3 M 1 Ax pH = -log[H"]=- log ((1.592 +0.008)x10-) log(x+4x) = log(x)=303 1 0.008 log((1.592+0.008)*10**) = log (1.592x10-):- 1-2.303 1.592 log((1.592 +0.008)x10-3) =-2.798057+0.002182 pH = -log((1.592 +0.008)x10-)= 2.798057 +0.002182 pH = 2.798 +0.002 The calculated value is rounded to 4 sig.fig. and the uncertainty is rounded to 1 sig.fig.