• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Analysing; Enthalpy of Decomposition of Sodium Hydrogencarbonate

Extracts from this document...

Introduction

Skill 3: Analysing; Enthalpy of Decomposition of Sodium Hydrogencarbonate Procedures and results Sodium Carbonate experiments Chemical Mass of Cup (grams) Mass of solid + cup (grams) Mass of solid (grams) Na2CO3 1.041 3.541 2.500 Na2CO3 1.114 3.514 2.500 Na2CO3 0.935 3.435 2.500 Table of results Time Experiment 1 Experiment 2 Experiment 3 Temp. of solid (0C) Temp. of solution (0C) Temp. of solid (0C) Temp. of solution (0C) Temp. of solid (0C) Temp. of solution (0C) 0 21.2 21.0 21.2 20.0 21.2 20.0 1 - 21.0 - 20.0 - 20.0 2 - 21.0 - 20.0 - 20.0 3 - 21.0 - 20.0 - 20.0 4 - - - - - - 5 - 25.5 - 25.0 - 25.0 6 - 25.0 - 24.4 - 24.0 7 - 24.8 - 24.2 - 24.0 8 - 24.6 - 24.0 - 23.8 9 - 24.5 - 24.0 - 23.8 10 - 24.5 - 23.9 - 23.6 Analysis Mr. of Sodium Carbonate = 2 x Ar (Sodium) + Ar (Carbon) + 3xAr (Oxygen) = 2 x 23.0 + 12.0 + 3 x 16.0 = 106 Moles of sodium carbonate used = mass of solid used Mr = 2.500/106 = 0.0235 mol Mass of acid = volume x density = 30.00 x 1 = 30.0 grams Mass of Solution = mass of acid + mass of solid = 30.0 + 2.500 = 32.5 grams The same amount of acid and solution was used throughout the 3 experiments Experiment 1 (T = T2 - T1 = 25.61 - 21.0 = 4.6 0C Energy transferred to surrounding = m x c x (T ...read more.

Middle

Maximum error of reading an apparatus = maximum error x 100 Amount read Maximum error of balance = 0.1/(the "difference" of 2 measurements) x 100 = 0.1/(1.0) x 100 = 10.0 % As per worksheet. However, in reality we used a more accurate balance that reads to 0.0001, thus, the reality maximum error of balance = 0.0001/1.0 x 100 = 0.01% Maximum error of burette = 0.15/30 x 100 = 0.50 % Maximum error of thermometer = 0.1/(the "difference" of 2 measurements) = 0.1/(24.5-13.8) = 0.93 % Maximum error from apparatus reading = sum of maximum errors = 10.0 % + 0.50% + 0.93% = 11.43 % There are other possible unquantified errors that could have interfered with the reaction; one main one would be heat loss. Heat loss cannot be quantified, as cannot be the methods in which the graphs were extrapolated, thus reduces the inaccuracies of this experiment. There could have also been substances, in particular solids that were left in the washing cup, despite the fact that I tried to use all the solid and use the "wash" the cup with some acid that I had previously extracted from the given amount of 30.00 ml. Skill 4: Evaluation; Enthalpy of Decomposition of Sodium Hydrogencarbonate Look at your graphs and comment on your results. Are you lines of best fit good enough for you to extrapolate the confidence? Are there any anomalous results? Suggest 1 possible reason for your anomalous result even if your results are within tolerance! ...read more.

Conclusion

Also, as I measured 2 things, different thermometer gives out different results, thus it was hard to determine whether the temperature difference would be acceptable. It could be avoided by using the same temperature, but not forgetting to wipe the acid or bases off (wash and clean the thermometer before measuring another chemical). The timescale of that was involved could have also been misleading, we recorded the temperature every minute, while the reaction could have occurred for a scale of, probably 15-20 seconds, thus, it would probably be better if we had recorded the temperature at a shorter time scale difference, over a longer period. Because the timescale we used may have bee too short, and maybe by using a longer time span, for example, 15 minutes, we could have mead the patterns and trends of the cooling curve more apparent. There could have also been substances, in particular solids that were left in the washing cup, despite the fact that I tried to use all the solid and use the "wash" the cup with some acid that I had previously extracted from the given amount of 30.00 ml. A way of avoiding this is to ensure that the weighing cup is properly rinsed with the acid, and that the entire solid is included in the reaction mixture. Other ways of improving this experiment would include the use of a pipette instead of a burette to measure out the acid, as it gives off a more accurate reading. Using a higher concentration of both acids and bases, to ensure reaction to occur, and the use of more standard conditions in the lab. 1 Estimated using regression line equation- see appendix A ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Aqueous Chemistry section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related GCSE Aqueous Chemistry essays

1.  ## Enthalpy of Neutralisation.

3 star(s)

(For example, a mixture of hydrogen and oxygen at room temperature). * Predictions from ?Hf? values relate only to standard conditions, i.e. 298 K and atmospheric pressure. The situation may be very different under different conditions or in the presence of a catalyst.

2. ## The aim of this experiment is to find the enthalpy change for the decomposition ...

If you are cut by glass rinse the cut under water immediately as it could be dangerous especially if you are dealing with chemicals. If there are any chemical spillages on the table tell the lab technicians, unless you know what it is don't attempt to clean it up, and

1. ## An Experiment to Determine the Enthalpy Change for the Decomposition of Calcium Carbonate.

The thermometer should not be left unsupported or it may topple over and break. Step 4 Add the weighed portion of CaCO3 to the HCl (hydrochloric acid) carefully. Immediately replace the lid of the polystyrene beaker. Then stir the mixture, then take the highest or lowest temperature and record this value in a table.

2. ## Indirect determination of enthalpy change of decomposition of sodium hydrogen carbonate by thermochemical measurement ...

100cm3 of 2M hydrochloric acid Implementation & Analysis Procedure for Experiment 1: with sodium hydrogen carbonate Initially, I gathered all the necessary apparatus together and set up my calorimeter. I ensured that the polystyrene cup was clean and intact, that the lid was secure and was pierced correctly so that I could fit a thermometer through the hole.

1. ## How much Iron (II) in 100 grams of Spinach Oleracea?

Justifications In order to dilute down the Iron (II) Ammonium Sulphate (aq) into various solutions of different concentrations a certain amount had to be removed from the original solution and placed in a volumetric flask, which was filled up to the graduation mark with Sulphuric Acid (aq).

2. ## Explain how the enthalpy change of neutralisation can be used to determine the relative ...

= 135 x 1.00 = 135g Grams (50cm3) = 135 ? 20 = 6.75g Next a measuring cylinder will be filled with an accurate 50cm3 of distilled water. The unknown acid solute will then be poured into a clean 100cm3 beaker (labelled U).

1. ## Finding the enthalpy of decomposition of Sodium Hydrogencarbonate

calculate the molarity using the formula: Molarity of acid = moles of acid x 1000 Volume Putting my values in I get: Molarity of acid = 0.2466 x 1000 250 = 0.9864 mol dm From this information I can now start to calculate to enthalpy change per mole of acid

2. ## Energy Change Associated With Neutralisation

To dilute my acid I will use water. For example if the strength of the acid is to be 1.00m then I will use 20ml of acid and 20ml of water for my solution. The alkali I will be using is sodium hydroxide. I will have a 500ml beaker of 2m acid, a 500ml beaker of 2m alkali and three other beakers. • Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to 