This document contains a 6-part stoichiometry exam with multiple choice and written response questions. The exam covers topics such as the law of constant composition, balancing chemical equations, empirical and molecular formulas, limiting reagents, percentage yield calculations, and methods for preparing different types of salts.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
1. Stoichiometry
Question Paper 2
Level IGCSE
ExamBoard CIE
Topic Stoichiometry
Sub-Topic
Paper (Extended) Theory
Booklet Question Paper 2
78 minutes
/ 65
TimeAllowed:
Score:
Percentage: /100
Subject Chemistry
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2. 1 The law of constant composition states that all pure samples of a compound contain the same
elements in the same proportion by weight.
A typical experiment to test this law is to prepare the same compound by different methods
and then show that the samples have the same composition.
Methods of making copper(II) oxide include:
• heating copper carbonate,
• heating copper hydroxide,
• heating copper nitrate,
• heating copper foil in air.
(a) Complete the following equations.
(i) CuCO3 → ............. + ............. [1]
(ii) Cu(OH)2 → ............. + .............
[1]
(iii) 2Cu(NO3)2 → ............. + 4NO2 + .............
[2]
(b) Copper oxide can be reduced to copper by heating in hydrogen.
(i) What colour change would you observe during the reduction?
.......................................................................................................................................
[1]
(ii) Explain why the copper must be allowed to cool in hydrogen before it is exposed to air.
.......................................................................................................................................
[2]
(iii) Name another gas which can reduce copper(II) oxide to copper.
.......................................................................................................................................
(iv) Name a solid which can reduce copper(II) oxide to copper.
.......................................................................................................................................
[1]
[1]
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3. (c) The table below shows the results obtained by reducing the copper(II) oxide
(ci) produced by different methods to copper.
(i) Complete the table.
source of copper(II)
oxide
mass of
copper(II) oxide/g
mass of
copper/g
percentage
copper/%
CuCO3 2.37 1.89 79.7
Cu(OH)2 2.51 1.99
Cu(NO3)2 2.11 1.68
Cu and O2 2.29 1.94
[2]
(ii) One of the samples of copper(II) oxide is impure.
Identify this sample and suggest an explanation why the percentage of copper in this sample is
bigger than in the other three samples.
.............................................................................................................................................
....................................................................................................................................... [2]
[Total: 13]
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4. 2 (a) A compound X contains 82.76% of carbon by mass and 17.24% of hydrogen by mass.
(i) Calculate the empirical formula of compound X.
[2]
(ii) Compound X has a relative molecular mass of 58.
Deduce the molecular formula of compound X.
[2]
(b) Alkenes are unsaturated hydrocarbons.
(i) State the general formula of alkenes.
....................................................................................................................................... [1]
(ii) State the empirical formula of alkenes.
....................................................................................................................................... [1]
(c) What is meant by the term unsaturated hydrocarbon?
unsaturated ................................................................................................................................
....................................................................................................................................................
hydrocarbon ...............................................................................................................................
....................................................................................................................................................
[2]
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5. (d) Describe a test that would distinguish between saturated and unsaturated hydrocarbons.
reagent ......................................................................................................................................
observation (saturated hydrocarbon) .........................................................................................
observation (unsaturated hydrocarbon) .....................................................................................
[3]
(e) Addition polymers can be made from alkenes. The diagram shows part of an addition polymer.
C
H
C2H5 H C2H5 H
H H H
C C C
[1](i) Draw a circle on the diagram to show one repeat unit in this polymer.
(ii) Give the structure and the name of the monomer used to make this polymer.
structure
name ............................................................................................................................. [2]
(iii) Give the structure of an isomer of the alkene in (e)(ii).
[1]
[Total: 15]
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6. 3 Ethanol is manufactured from glucose, C 6H12O6, by fermentation according to the following
equation. C6H12O6 → 2C2H5OH + 2CO2
(a) State the conditions required for this reaction.
....................................................................................................................................................
.............................................................................................................................................. [2]
(b) In an experiment, 30.0g of glucose was fermented.
(i) Calculate the number of moles of glucose in 30.0g.
......................... mol [2]
(ii) Calculate the maximum mass of ethanol that could be obtained from 30.0g of glucose.
......................... g [2]
(iii) Calculate the volume of carbon dioxide at room temperature and pressure that can be
obtained from 30.0g of glucose.
......................... dm3
[1]
(c) Ethanol can also be manufactured from ethene.
(i) Name the raw material which is the source of ethene.
....................................................................................................................................... [1]
(ii) Write a balanced equation for the manufacture of ethanol from ethene.
....................................................................................................................................... [1]
[Total: 9]
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7. 4 (a) Definethefollowing
(i) the mole
....................................................................................................................................
.............................................................................................................................. [1]
(ii) the Avogadro constant
....................................................................................................................................
.............................................................................................................................. [1]
(b) Which two of the following contain the same number of molecules?
Show how you arrived at your answer.
2.0g of methane, CH4
8.0g of oxygen, O2
2.0g of ozone, O3
8.0g of sulfur dioxide, SO2
...........................................................................................................................................
...........................................................................................................................................
..................................................................................................................................... [2]
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8. (c) 4.8g of calcium is added to 3.6g of water. The following reaction occurs.
Ca + 2H2O → Ca(OH)2 + H2
(i) the number of moles of Ca = ....................
the number of moles of H2O = .................... [1]
(ii) Which reagent is in excess? Explain your choice.
....................................................................................................................................
.............................................................................................................................. [2]
(iii) Calculate the mass of the reagent named in (ii) which remained at the end of the
experiment.
....................................................................................................................................
.............................................................................................................................. [1]
[Total: 8]
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9. 5 Quantities of chemicals, expressed in moles, can be used to find the formula of a
compound, to establish an equation and to determine reacting masses.
(a) A compound contains 72% magnesium and 28% nitrogen. What is its empirical
formula?
[2]
(b) A compound contains only aluminium and carbon. 0.03moles of this compound reacted
with excess water to form 0.12moles of Al(OH)3 and 0.09moles of CH4.
Write a balanced equation for this reaction.
[2]
(c) 0.07moles of silicon reacts with 25g of bromine.
Si + 2Br2 SiBr4
(i) Which one is the limiting reagent? Explain your choice.
[3]
(ii) How many moles of SiBr4 are formed?
[1]
[Total: 8]
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10. 6 (a The following method is used to make crystals of hydrated nickel sulphate.
An excess of nickel carbonate, 12.0 g, was added to 40 cm3
of sulphuric acid, 2.0
mol/dm3
. The unreacted nickel carbonate was filtered off and the filtrate evaporated to
obtain the crystals.
NiCO3 + H2SO4
NiSO4 + 7H2O
NiSO4 + CO2 + H2O
NiSO4.7H2O
Mass of one mole of NiSO4.7H2O = 281 g
Mass of one mole of NiCO3 = 119 g
(i) Calculate the mass of unreacted nickel carbonate.
g
Number of moles of H2SO4 in 40 cm3
of 2.0 mol/dm3
acid = 0.08
Number of moles of NiCO3 reacted =
Mass of nickel carbonate reacted =
Mass of unreacted nickel carbonate = g [3]
(ii) The experiment produced 10.4 g of hydrated nickel sulphate. Calculate the
percentage yield.
The maximum number of moles of NiSO4 .7H2O that could be formed =
gThe maximum mass of NiSO4 .7H2O that could be formed =
The percentage yield = % [3]
(b) In the above method, a soluble salt was prepared by neutralising an acid with an
insoluble base. Other salts have to be made by different methods.
(i) Give a brief description of how the soluble salt, rubidium sulphate could be made
from the soluble base, rubidium hydroxide.
[3]
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11. (ii) Suggest a method of making the insoluble salt, calcium fluoride.
[3]
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![1 The law of constant composition states that all pure samples of a compound contain the same
elements in the same proportion by weight.
A typical experiment to test this law is to prepare the same compound by different methods
and then show that the samples have the same composition.
Methods of making copper(II) oxide include:
• heating copper carbonate,
• heating copper hydroxide,
• heating copper nitrate,
• heating copper foil in air.
(a) Complete the following equations.
(i) CuCO3 → ............. + ............. [1]
(ii) Cu(OH)2 → ............. + .............
[1]
(iii) 2Cu(NO3)2 → ............. + 4NO2 + .............
[2]
(b) Copper oxide can be reduced to copper by heating in hydrogen.
(i) What colour change would you observe during the reduction?
.......................................................................................................................................
[1]
(ii) Explain why the copper must be allowed to cool in hydrogen before it is exposed to air.
.......................................................................................................................................
[2]
(iii) Name another gas which can reduce copper(II) oxide to copper.
.......................................................................................................................................
(iv) Name a solid which can reduce copper(II) oxide to copper.
.......................................................................................................................................
[1]
[1]
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