Volumetric Analysis Practical To determine the pH of commercially supplied 32% Hydrochloric acid solution. Investigative question Can the pH of an acid which is Hydrochloric acid be calculated by using titration with a standardized base solution of Sodium Hydroxide? Hypothesis That the pH of the hydrochloric acid solution can be calculated using titration with a standardised sodium hydroxide base solution as long as concentration and temperature of base solution remain constant. Variables Independent variable Volume of base (sodium hydroxide) needed to titrate the acid solution Dependant Variable Volume of acid (hydrochloric acid) placed in beaker to be titrated. Controlled variables • Concentration of base • Temperature of chemicals • Same indicator used • Chemicals obtained from the same bottles • Same measuring apparatus used Apparatus • 2x burette • 2x retort stand • 2x clamp • 6x conical flask • 2x round bottom flask • 2x pipette • 1x measuring cylinder • 1x spatula • 1x electronic scale • 2x beaker • 1x Erlenmeyer flask • 4x 250ml volumetric flask • 10ml Bromothymol blue • 3x oxalic acid crystals • 3x Sodium hydroxide pellets • 1 Bottle Hydrochloric acid solution • 1x Thermometer • 1x video camera • 1x dropper Diagram Method Safety precautions 1. Plugging the beakers containing chemicals 2. Using tongs to pour chemicals 3. Keeping eyes and nose away from the opening of the beakers 4. Standing away from the work table when not working on the experiment 5. Wear thin rubber gloves 6. Wear a lab coat 7. Remove ties 8. Wear safety goggles 9. Be aware of acid burns from hydrochloric acid. Accuracy precautions 1. Using the same measurin... ... middle of paper ... ...ransfer of substances like sodium chloride from a measuring beaker to a flask in which to conduct the experiment results in trace particles being left in the beaker. This alters the number of moles in the solution altering concentration and therefore results. Bibliography • Acid Base Titration (Theory) : Inorganic Chemistry Virtual Lab : Chemical Sciences : Amrita Vishwa Vidyapeetham Virtual Lab . 2014. Acid Base Titration (Theory) : Inorganic Chemistry Virtual Lab : Chemical Sciences : Amrita Vishwa Vidyapeetham Virtual Lab . [ONLINE] Available at: http://amrita.vlab.co.in/?sub=2&brch=193&sim=352&cnt=1. [Accessed 25 May 2014]. • Aqueous Acid-Base Equilibria and Titrations. Levie, Robert De. New York : Oxford University Press, 1999. • Reactions of Acids and Bases in Analytical Chemistry. Hulanicki, A. and Masson, M.R. New York: Halsted Press, 1987.
This means that there are more collisions between the solid and liquid. Amount of tap water H2O used, i.e. volume (in ml) of the syringe. Amount of Alka-Seltzer tablets used, i.e. quantity of the tablets. one is used for the. Number of times the solution is stirred.
Repeat for each trial. Rinse volumetric pipette with vinegar and drain into the waste beaker. Weigh and record the mass of each 200mL beaker. Add 10.00mL of vinegar into each beaker and weigh them and record their again. Add 50mL of de-ionized water to the beakers and place them under the drop counter on top of a stir plate, submerging the pH meter into the solution. Place the stir bar into the beaker and carefully turn on the stir plate so that the stir bar spins without splashing or hitting the sides of the beaker or the pH
As shown in Fig. 5, the final pH of the NaClO-NH3 solution after simultaneous removal are 5.4, 6.9, 7.2, 7.5, 8.5, 9.6, 10.7, 11.5 and 12.8 with respect to the initial pH of 5, 6, 7, 8, 9, 10, 11, 12 and 13, from which, an interesting law can be concluded as that if the initial pH is an acidic, the final pH is slightly increased; but if the initial pH is an alkaline, the final pH is declined. NaClO-NH3 is macromolecule compounds with a large inter surface area. It contains abundant functional groups such as hydroxyl (OH), carboxyl (COO), quinone, amino (–NH2), etc, which determines that NaClO-NH3 is a salt of strong base and weak acid, as well the ionization equilibrium and hydrolytic equilibrium would be complicated. When the pH of the NaClO-NH3 solution was acidic, the functional groups such as OH, COO and NH2- would react with H+ to generate the NH3 sediment, resulting in a decrease of inter surface area owing to the block and a great loss of NaClO-NH3, then the NOx removal as well as the duration time was decreased. As for the increase of the final pH in the acidic conditions, this was a result of the consumption of H+ by NaClO. The decrease of the
We were then to make a base solution of 0.7 M NaOH. In order to standardize
Planning Firstly here is a list of equipment I used. Boiling tubes Weighing scales Knife Paper towels 100% solution 0% solution (distilled water) measuring beakers potato chips Cork borer. We planned to start our experiment by doing some preliminary work. We planned to set up our experiment in the following way.
In this experiment, there were several objectives. First, this lab was designed to determine the difference, if any, between the densities of Coke and Diet Coke. It was designed to evaluate the accuracy and precision of several lab equipment measurements. This lab was also designed to be an introduction to the LabQuest Data and the Logger Pro data analysis database. Random, systematic, and gross errors are errors made during experiments that can have significant effects to the results. Random errors do not really have a specific cause, but still causes a few of the measurements to either be a little high or a little low. Systematic errors occur when there are limitations or mistakes on lab equipment or lab procedures. These kinds of errors cause measurements to be either be always high or always low. The last kind of error is gross errors. Gross errors occur when machines or equipment fail completely. However, gross errors usually occur due to a personal mistake. For this experiment, the number of significant figures is very important and depends on the equipment being used. When using the volumetric pipette and burette, the measurements are rounded to the hundredth place while in a graduated cylinder, it is rounded to the tenth place.
For this experiment we have to use physical methods to separate the reaction mixture from the liquid. The physical methods that were used are filtration and evaporation. Filtration is the separation of a solid from a liquid by passing the liquid through a porous material, such as filter paper. Evaporation is when you place the residue and the damp filter paper into a drying oven to draw moisture from it by heating it and leaving only the dry solid portion behind (Lab Guide pg. 33.).
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.
Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment.
EDTA Titrations [homepage on the internet]. No date. [cited 2014 Mar 24]. Available from: http://bionmr.unl.edu/courses/chem221/lectures/chapter-12.ppt.
Safety remains one of the key elements in modern school labs; it is necessary for the staff to ensure the safety of all the lab users. Every chemical and equipment in the laboratory have the potential to harm if adequate safety measures are not taken into account. As lab uses, you have to consider that you follow the basic safety guidelines for the lab sessions. Always be aware of all the general safety precaution and familiarize yourself with the appropriate protective measures that can keep you safe (NIOSH, 2006). It is important to consider that serious damage could occur if the basic safety rules and regulations for lab practice are not followed. It is in this light that a clear guideline for safety and protection
The titration of a weak acid with a strong base produces a titration curve as above.
Firstly, we need to keep the chemical at a constant concentration. So, in this experiment we have chosen to keep hydrochloric acid at a constant concentration (5cm3). We could have, however, used Sodium Thiosulphate as a constant, but we had chosen to use Hydrochloric acid. Next, we must make sure that the solution is kept at a constant volume throughout the experiment. If the volume is different, then it could give different results if it was at a constant volume.
In this experiment three different equations were used and they are the Stoichiometry of Titration Reaction, Converting mL to L, and Calculating the Molarity of NaOH and HCl (Lab Guide pg. 142 and 143).