Distinguish between the fce l1pi3 uc93following terms:
1.Precision and accuracy.
2.Systematic error and random error.

  A student conducted a titratio8 cqp: 3dl*c0fq pj3uzn experiment. However, instead of rinsing his apparatus with distilled water, he rinses them with tap water onlu:qz0q 3p 8* fcd3lpjcy. What is likely the type of error?

A student is determining the ri1ofx3y8p :/7k pjtin ate of the reaction between $MgCO_3$ and HCl. List 3 sources of random errors.

  The diameter of a cylindrical sample was measured using a vernier caliper agbc6 ;1fy-q-: das. 9sz-k h wcqkenh4t three different points a.w1 c-q:4 gksash; zqe6-ynbf-d9kc hlong the sample. The diameters measured were: 13.50 mm, 13.51 mm, 13.50 mm. The true diameter of the sample is 12.14 mm. What is the likely type of error, and how can the error be reduced?

  The enthalpy of neutralizav2ecs magt* w60h.p2j tion for the reaction between sulfuric acid and potassium hydroxide can be determined experimentally. cmgav.wj0e tp622* s h
$H_2SO_4$(aq)+2KOH(aq)→$K_2SO_4$(aq)+2$H_2O$(l)
A student recorded the temperature of 20.0 cm$^3$ of 0.500 mold m$^{-3}$ sulfuric acid every minute. At four minutes,25.0cm$^3$ KOH(aq) is added to the solution, stirred immediately, and temperature recorded for another four minutes. The results are represented in the graph below.



1.Calculate the lowest concentration of aqueous KOH that must be used to ensure it is in excess.
n$_{KOH}$=  mol;C$_{KOH}$=  mold m$^{-3}$
2.Use the graph above to estimate a value for the maximum temperature change, ΔT.
ΔT=  °C
3.State one assumption you made in part (b).
4.Identify the anomalous result and suggest a possible type and source of error.
5.In another experiment with the same reactants, the student measured the initial and final temperatures and presented their results below:
Initial Temperature (°C ± 0.1°C) 24.8 25.1 24.9
Final Temperature (°C ± 0.1°C) 26.4 26.6 26.4
5.1.Calculate the average change in temperature (ΔT) giving its percentage uncertainty.
Average=  °C
5.2.Use sections 1 and 2 of the data booklet to calculate the energy released and its uncertainty. You may assume that the only source of uncertainty is from the temperature change.
Energy released (q)=  J

  25.00 cm$^3$ of 0.100 mold m$^{-3}$$HNO_3$ was titrated against 0.200 mold m$^{-3}$$NaOH$.The volumes of NaOH delivered for the three trials 14.00 cm$^3$ ,14.05 cm$^3$ and 14.00 cm$^3$.
Which statement below best describes these results?