Notes, summaries, assignments, exams, and problems for Chemistry

Relative Molecular Mass and Composition

60.The relative molecular mass of aluminium chloride is 267 and its composition by mass is 20.3%....

moles of Na == 0.05;

moles of NaOH = 0.05; same as moles of Na.concentration == 0.20 (mol dm–3)3

Reaction of Sodium with Water

61.Sodium reacts with water as follows.2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)

1.15 g of sodium....

AlCl .empirical formula AlCl3;molecular formula: n = = 2;Al2Cl6

Reaction of Calcium Carbonate with Acids

62.(i)Calcium carbonate is added to separate solutions of hydrochloric acid and ethanoic.....bubbling/effervescence/dissolving of CaCO3/gas given off 

more vigorous reaction with HCl/OWTTE;2

(ii)2HCl(aq) + CaCO3(s)  CaCl2(aq) + CO2(g) + H2O(1); 

(iii)amount of CaCO3.amount of HCl... Continue reading "Chemical Reactions and Energy Changes" »

Pure Substances and Mixtures

Pure substances: A pure substance has a constant composition that does not vary when subjected to physical changes.

Mixtures: A mixture can be separated by physical changes, such as filtering or boiling.

Elements and Compounds

Element: An element is a pure substance consisting of a single type of atom.

Compound: A compound is a pure substance consisting of two or more types of atoms linked together by chemical bonds.

Composition of the Universe, Earth, and Humans

• Universe: Hydrogen (73.9%), Helium (24%), Other (2%)
• Earth: Oxygen (29.7%), Iron (31.9%), Silicon (16.1%), Magnesium (15.4%), Other (6.4%)
• Human Being: Oxygen (65%), Carbon (18%), Hydrogen (10%), Nitrogen (3%), Other (3.4%)

The Periodic Table

Periodic Table: The periodic... Continue reading "Elements, Compounds, and the Periodic Table" »

Unit 1: Memory and Experience Vocabulary

Key Vocabulary for Memory and Recollection

• remember: recordar
• recall: traer de la memoria
• record: grabar
• appointments: citas
• diary: diario
• memorize: memorizar
• memory: memoria
• memories: recuerdos
• calendar: calendario
• remind: recordar
• mind: mente
• forget: olvidar
• learn: aprender
• by heart: de memoria

Phrasal Verbs Related to Action and Resolution

• carry out: llevar a cabo
• let something down: decepcionar
• sort out: ordenar/preparar
• work out: resolver

Common False Friends in English

• anxious: nervioso vs. eager: ansioso
• success: éxito vs. event: suceso
• embarrassed: avergonzado vs. pregnant: embarazada

Expressing Feelings and Emotions

Intensity of Feelings: From Mild to Strong

• angry/cross → furious
• upset → heartbroken/devastated
• frightened/

Atom

The smallest particles a simple substance can be divided into without losing its chemical properties.

Chemical Element

A chemical element is a species of atoms having the same number of protons in their atomic nuclei.

Subatomic Particles

• Electrons: negative charge, no mass
• Protons: positive charge, mass
• Neutrons: no charge, mass equal to protons.

Atomic Models

• Plum Pudding Model: a sphere of positive electricity with neutrons
• Rutherford's: each electron had an orbit
• Bohr's: each orbit presents a different number of electrons.

To differentiate an atom from others, the number of protons and neutrons it has in its nucleus.

Atomic Number

Number of protons in the nucleus of an atom (Z).

Mass Number

The number of protons and neutrons in the nucleus of an atom... Continue reading "Understanding Atoms, Elements, and Bonds in Chemistry" »

Matter: pure substances: element and compound

           mixture: homogeneous mixture and heterogeneous mixture

A pure substance is a substance made of only one kind of matter and having definite properties. An element is composed of a ingle kind of atoms. A compound is composed of two or more elements in a specific ratio. Chemists cant easily separate the components of a compound. Mixtures are physical combinations of pure substances. Different parts of a mixture can be easily separated by physical means. A heterogeneous mixture is a mixture whose composition varies from position to position within the sample. A homogeneous mixture sometimes called solution is relatively uniform in composition. Solvent and solute.

State: solid Solvent:... Continue reading "Coh3 compound name" »

Unit 4: Atoms and Their Models

UNIT 4

Atoms are the basis of all the structures and organisms in the universe.

2. Models of the Atom

A model is a representation of a system in the real world. Models help us to understand systems and their properties.

2.1 Dalton's Model of the Atom

John Dalton proposed that all matter is composed of very small things which he called atoms.

2.2 Thomson's Model of the Atom

In this model, the atom is made up of negative electrons that float in a soup of positive charge, much like plums in a pudding or raisins in a fruit cake.

2.3 Rutherford's Model of the Atom

His new model described the atom as a tiny, dense, positively charged core called a nucleus surrounded by lighter, negatively charged electrons.

2.4 Bohr's Model of

• Lexeme: The abstract vocabulary item listed in the lexicon with a common core of meaning.
• Word-forms: Physical realizations of the lexeme.
• Paradigm: The list of word-forms that belong to a word.
• Morpheme: The smallest unit of analysis with semantic content or grammatical function that words are made up of.
• Morph: The physical realization of the morpheme. Morphs are made up of one or more morphemes.
• Syncretism: Identical word-forms that belong to the same lexeme but are different grammatical words.
• Root: The basic form that remains when you get rid of all the affixes.
• Stem: A term that we only use in inflectional morphology; it is the form to which you attach an inflectional affix (only suffixes in English).
• Base: Anything; any root and any stem are

Intermolecular Forces (IMFs)

IMFs include: Covalent, Hydrogen, Metallic, Dipole, London, and Ion interactions.

Solution Chemistry Formulas

• pH (Acidic Solutions): $\text{pH} = -\log[\text{H}^+] = -\log N = \text{p}H_A = \sqrt{K_a M}$ (where $K_a = x^2/M$ and $-\log x = \text{p}OH$ is incorrect in this context, use $\text{pH} = 14 - \text{pOH}$)
• pOH (Basic Solutions): $\text{pOH} = -\log[\text{OH}^-] = -\log N$. For weak bases (WB): $K_b = x^2/M$ and $-\log x = \text{pOH}$, leading to $\text{pH} = 14 - \text{pOH}$.

Strong Acids

Common strong acids include: $\text{HNO}_3$, $\text{H}_2\text{SO}_4$, $\text{HBr}$, $\text{HI}$, $\text{HClO}_4$, and $\text{HClO}_3$.

Lewis Acid

A compound or ionic species that can accept an electron pair from a donor compound.... Continue reading "Chemical Bonding and Solution Chemistry Concepts" »

1.Who propossed the theory of One-dimensional consolidation? Karl Terzaghi

2.What types of permeameters exist in Lab tests? Constant head permeameter and Failing head permeameter

3.What is the name of the equation that Governs the 2D underground flow? Laplace’s Equation.

4.Name of the method of draw flow nets That uses iterative calculations. Finite Differences

5.What are the units of the compression Index Cc? Adimensional, NOT UNITS

6.Describe boiling in soils. Boiling of soils occurs when there is an Upward flow and the seepage force is greater that the submerged weight of the Soil.

7.What are the assumptions in laplace’s Equation. Darcy’s law applies, Water and Solids are uncompressible

8.When in it better to use failing head permeameter?

Water Quality and Treatment Fundamentals

1. Eutrophication

What does the term eutrophication refer to?
An excess of algae growth due to inorganic nutrients.

2. Turbidity and Solubility

What type of particles are responsible for turbidity?
Particulate non-settleable compounds.

If the partial pressure of a gas increases, the solubility in water of the gas:
Increases.

3. Environmental Impacts

Which of the following is an effect of eutrophication?

• Increase of pH in water where there is eutrophication.
• Bacteria consume the oxygen in water by degrading dead plants.
• Plants do not grow due to a lack of sunlight.

Which of the following is an effect of thermal pollution?
Lack of O₂ due to lower solubility of gases at high temperatures.

4. Water Chemistry and Directives

What