Lesson 13.6 Changes of physical state: * necessary to draw a temperature-energy graph to see the change in temperature with a constant application of heat Heat of fusion - the amount of heat required to melt 1.00 g of substance. substance changing from a solid to a liquid. Heat of vaporization - the amount of heat required to vaporize 1.00 g of a substance. substance changing from a liquid to a gas. heats of vaporization and condensation are equal.
D) It conducts electricity when dissolved in water. E) none of the above 4. In a Lewis dot structure the electrons which complete an octet but are not located between two atoms are referred to as A) bonding pairs. B) delta minus electrons. C) excess electrons.
A) Hydrogen bonds are strong enough to confer structural stability, for example in DNA. B) Hydrogen bonds are weak enough to be easily broken (weaker than covalent bonds). C) They contribute to the water solubility of many macromolecules. D) All of the above Answer: D Page Ref: Section 5 27) London dispersion forces are attractive forces that arise due to A) infinitesimal dipoles generated by the constant random motion of electrons. B) permanent dipoles of molecules containing covalent bonds between atoms of very different electronegativities.
When atoms bond together they share or transfer electrons to achieve a more stable electron arrangement, often a full outer main level of electrons, like the noble gases. There are three types of strong chemical bonds: 1.__ionic______, 2.____covalent____ and metallic IONIC bonding • Ionic bonding occurs between metals and non-metals • Metal atoms 3. ___lose___ electrons • Non-metal atoms gain electrons • Positive and negative ions are formed Sodium chloride has ionic bonding. [pic] • The sodium ion is positively charged because it has lost a negative electron
For example, the reaction |BaCl2•2H2O ( BaCl2 + 2H2O |(2) | is reversible, and if water is added to the anhydrous salt BaCl2, formation of BaCl2•2H2O takes place: |BaCl2 + 2H2O ( BaCl2•2H2O |(3) | The reaction of dehydration of hydrated ferrous sulfate |FeSO4•7H2O ( FeSO4 + 7H2O |(4)
Name: ___________________________________ Date: ______________ Practice Test #3 ____ 1. When a precipitation reaction occurs, the ions that do not form the precipitate A) evaporate B) are cations only C) form a second insoluble compound in the solution D) are left dissolved in the solution E) none of these 2. An aqueous solution of potassium chloride is mixed with an aqueous solution of sodium nitrate. The complete ionic equation contains which of the following species (when balanced in standard form)? A) B) C) D) E) ____ 3.
Polar bonding is with an unequal sharing of electrons between two different nonmetals. The number of shared electrons depends on the number of electrons needed to complete the shell. Non-polar bonding with an equal sharing of electrons between identical nonmetals (R. Nave). A covalent bond is between two nonmetals. Whereas an ionic bond is between a positive metal and a negative non- metal.
Distillation is a liquid purification process using heating and cooling. Real World Application Vapor pressure is used in distillation to purify a compound by separating it from non-volatile material. The lowering of the vapor pressure causes molecular movement along the surface of a liquid and through processes of evaporation and vapor cooling; the compound is separated and distilled into its purer forms. Distillation there are many uses for colligative properties in the real world, and decreasing of vapor pressure is among the many that are implemented into modern techniques and technology today. "Colligative Properties of Solutions."
The dissolving process involves a consideration of the relative strength of three intermolecular attractive forces. The type of forces between solute-solute molecules and solvent-solvent molecules must be considered. These intermolecular attractions must be broken before new solute-solvent attractive forces can become effective. A solute will dissolve in a solvent
It is based on the manipulation of the solubility at various temperatures. To have an successful recrystallization of the solid, there has to be an ideal solvent meaning the liquid in which the solid or solute is infinitely insoluble at room temperature and infinitely soluble at high temperature. This experiment will determine if the Benzoic acid will truly be soluble in the polar solvent such as water. It will also show the efficiency of the recrystallization process by comparing the experimental and literature values of melting point of the pure benzoic acid. Experimental: The experiment started with measuring the melting point range of impure benzoic acid.