• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3
4. 4
4
5. 5
5

# To determine the enthalpy of reaction.

Extracts from this document...

Introduction

Lewisham College Zahra Hussien As chemistry Assessor: Bernice Ferdinand Science investigation for OCR coursework As chemistry Title To determine the enthalpy of reaction Introduction The enthalpy change of reaction is the enthalpy change when amount of reactants react together under standard conditions to give products in their standard states. The heat change might be exothermic or endothermic. Exothermic reactions: Heat flows from the system to the surroundings. The value will be negative. Endothermic reactions: Heat flows from the surroundings into the system. The value will be positive. Aim The purpose of this experiment is to determine the enthalpy of the reaction for a displacement reaction: * CaCo3(s) + 2HCl(aq)? CaCl2(aq) + Co2(ga) + H2O(l) * CaO(s) + 2HCl(aq) ? CaCl2(aq) + H2O(l) By adding 2 mol/dm3 of HCl to a CaCo3 and CaO, and measure the temperature changes and calculates the enthalpy change for the reaction. Prediction I predict from the experiment I am going to do, I expect the reaction is going to be exothermic reaction in both CaCo3 and CaO. ...read more.

Middle

? CaCl2(aq) + H2O(l) * Find the number of moles for CaO n = m/M n = 2.52/52 n = 0.0485mol * Heat evolved during the reaction (?H2) ?H2 = mc?T2 ?H2 = 1.5 x 4.2 x (40.5oc-18oc) ?H2 = 141.75J ?H2 = 0.14175 kJ * Heat evolved per mol ?H2/n = 0.14175 kJ /0.0485 ?H2 = 2.92KJ/mol * ?H3 = ?H1 - ?H2 ?H3 = 0.84KJ/mol - 2.92KJ/mol ?H3 = -2.08KJ/mol > Glass beaker * CaCo3(s) + 2HCl? CaCl2(aq) + Co2(ga) + H2O(l) * Find the number of moles for CaCo3 n = m/M n = 2.52/100 n = 0.0252mol * Heat evolved in the reaction ?H1 = mc?T1 ?H1= 2.52 x 4.2 x (21oc-20oc) ?H1 = 10.584J ?H1 = 0.010584 kJ * Heat evolved per mol ?H1/n = 0.010584KJ/0.0252mol ?H1 = 0.42 KJ/mol * CaO(s) + 2HCl(aq) ? CaCl2(aq) + H2O(l) * Find the number of moles for CaO n = m/M n = 2.52/52 n = 0.0485mol * Heat evolved during the reaction (?H2) ?H2 = mc?T2 ?H2 = 1.5 x 4.2 x (36.5oc-18oc) ...read more.

Conclusion

* I use one thermometer to avoid any source of error. * I make sure the equipments were clean and dry. * I used a different weighing bottle to measure CaCO3 and CaO. * I was controlling my self when I was transferring those powders. However, there are a number of errors might happen during the experiment: 1. There is a transfer error; some amount of CaCO3, CaO remain in the weighing bottle while I was transferring to the glass beaker and polystyrene. 2. Reading of the thermometer (I can only read to accuracy of nearest degree). 3. Measuring of the weight of CaCO3 and CaO. 4. Some errors are likely to come from measurements. A source of error would be parallax error, which would involve the meniscus. Suggestions and Improvements - To create a more accurate experiment in the future, several precautions or alterations can be made: * Cover both polystyrene and glass beaker to avoid heat loss to the environment * Stir the solution in the same manner to get the maximum heat lost. * It will be a god idea to do the investigation more than one so that an average of heat loss could be calculated. ...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 Patterns of Behaviour 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 Patterns of Behaviour essays

1. ## The object of this investigation is to determine the enthalpy change for the reaction ...

= - 24.90 kJmol-1 3) If 2.50 g of CaCO3 then: moles of CaCO3 = 2.50 g ? 100 = 0.0250 moles. Seeing as the molar mass of CaCO3 = 100.00 ?H1 = 420 x (1 x 0.0250) = - 16.80 kJmol-1 I will not include the last result in my average for ?H1, which is - 16.80 kJmol-1.

2. ## Exothermic and endothermic reactions

[1 mark] The Answer Ca (calcium) Examiner's Note Well done. The group number (the figure at the top of each column) is the same as the number of electrons in the outer shell of the atoms in that group. For this reason, you could also have answered Mg (magnesium).

1. ## To Determine the Enthalpy Change of a Reaction.

Safety Apparatus: Safety glasses and lab-coat. The quantities of materials I have available: HCl (2.0 mol dm-3) : As much as required CaCO3 : Between 2.4g and 2.6g CaO : As much as required In order to determine the quantities I will need to use in the experiment, I must carry out a few simple calculations.

2. ## To determine the enthalpy change of a reaction.

I will do the following: 0.02mols: 105J I will divide both sides by 0.02mols 0.02/0.02: 105/0.02 1mol: 5,250.0J I will convert the answer into KJ by dividing the answer by 1000 So: 5,250.0/1000 = 5.25 kJmol-1 ?H1 = - 5.25 kJmol-1 The reaction is exothermic because there is a negative

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to
improve your own work