THEORY
1ai)
an acid base indicator is a weak acid or weak base that exhibits a colour change as the concentration of hydrogen (H^ ) or hydroxide (H^-) ions changes in an aqueous solution
1aii)
methyl-orange
1b)
i)oxidizing agent
ii)mixed anhydride
1c)
enthalpy of combustion is the heat evolved when one mole of a substance is completely burns in oxygen gas under standard conditions
1cii)
enthapy of combustion is always negetive since it involvs a rise in temperature and heat of reactants is greater than the heat of products
1d)
primary cell is a cell that cannot be re charged while secondary cell is a cell that can be recharge
1e)
mole is the unit of measurement in the International System of Units (SI) for amount of substance. The unit is defined as the amount of a chemical substance which contains as many representative particles, e.g., atoms, molecules, ions, electrons, or photons, as there are atoms in 12 grams of carbon-12 (12C), the isotope of carbon with relative atomic mass
1f)
n= V=40cm^3
c= 0.40moldm^3
n=cv/1000
0.40*40/1000 = 0.016mol
2ai)1 The Periodic Law states that the physical and chemical properties of the elements recur in a systematic and predictable way when the elements are arranged in order of increasing atomic number.
2ai)ii The periodic table arranges the elementsby periodic properties, which are recurring trends in physical and chemicalcharacteristics. ... These trends explainthe periodicity observed in the elementalproperties of atomic radius, ionization energy, electron affinity, and electronegativity.
2aii) Electron affinity
Ionization energy
Electronegativity
2aiii) ELECTRON AFFINITY
Electron affinity reflects the ability of an atom to accept an electron. It is the energy change that occurs when an electron is added to a gaseous atom.
Ionization energy:
Ionization energy is the energy required to remove an electron from a gaseous atom or ion. The first or initial ionization energy or Ei of an atom or molecule is the energy required to remove one mole of electrons from one mole of isolated gaseous atoms or ions.
Electronegativity:
Electronegativity is a measure of the attraction of an atom for the electrons in a chemical bond. The higher the electronegativity of an atom, the greater its attraction for bonding electrons.
2b) Relative atomic mass (symbol: Ar) is a dimensionless (number only) physical quantity. In its modern definition, it is the ratio of the average mass of atoms of an element in a given sample to one unified atomic mass unit.
5ai) worm the unknown substance with concentrated H2SO4 in a test tube. if trioxonitrate(v) ion's are/is present, some trioxonitrate(v) acid will be condensed as oily drops on the upper part of the tube. On further heating, the acid decomposes yielding brown fums of NO2 gas.
5iia) Sodium chloride is used for:
=preserving food
=glazing pottery
5iib) Sodium trioxocarbonate(iv) is used for:
=standardizing acids in the laboratory
=the manufacture of glass
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