Monday, April 28, 2008
Mon-Day 2
Bio- welcome back! Here is an awesome link to a site that tracks the genetic history of humans (Homo sapiens) and here is a link to a recent article about the near EXTINCTION of the human species that occurred just 70,000 years ago!
Today, we discussed the mechanism of evolution via natural (or artificial) selection. We looked at two of four explicit examples of change/evolution of a species:
1. evolution of the modern-day long-neck giraffe from the ancestral shorter-neck giraffe
2. evolution of the peppered-moth population due to human-caused (artificial) environmental change (pollution)
Using the Darwinian explanation along with some modern understanding of genes/alleles, we showed how variation (via MUTATION, sexual reproduction, environmental influences) overpopulation, competition, SELECTION, and speciation/evolution can occur.
In the peppered-moth example, though a new species did not develop, there was a significant change in the percentage of moths with the light-color alleles; this is still an example of evolution within a population.
Chem 7/8- SOLUTIONS EXAM will be given on Wednesday!
we discussed colligative properties: boiling point ELEVATION, freezing point DEPRESSION, and vapor pressure lowering and noted that the greater the CONCENTRATION of DISSOLVED particles (ions OR molecules), the GREATER the colligative EFFECTS.
We then discussed how SOLUBLE ionic compounds (salts and hydroxide bases) DISSOCIATE into separate ions when dissolving occurs, leading to a greater concentration of dissolved particles. Therefore, given the same number of moles dissolved, IONIC compounds have GREATER colligative effects than do molecular substances (which do NOT break apart into atoms or ions).
We also illustrated that soluble salts (e.g. NaCl, KOH, (NH4)2SO4) are STRONG electrolytes, forming concentrated saturated solutions of CHARGED ions capable of conducting electricity.
Insoluble salts (e.g. PbCl2, AgBr, BaSO4) are WEAK electrolytes, forming DILUTE saturated solutions i.e. LOW concentrations of ions, which causes little to no electrical conductivity.
Molecular substances (EXCEPT for ACIDS- compound formulas that begin with "H", e.g. HCl) are NON-electrolytes. Thus, when molecules are dissolved in water, NO IONS form because covalent bonds are not broken via dissolving. So, solutions of molecular substances (e.g. CH3OH, C6H12O6, CH4, CO2, N2, Cl2) do NOT conduct electricity and do not have as large a colligative effect as do STRONG electrolytes.
We then discussed our precipitation lab.
Chem 9- SOLUTIONS EXAM will be given on Wednesday!
we discussed colligative properties: boiling point ELEVATION, freezing point DEPRESSION, and vapor pressure lowering and noted that the greater the CONCENTRATION of DISSOLVED particles (ions OR molecules), the GREATER the colligative EFFECTS.
We then discussed how SOLUBLE ionic compounds (salts and hydroxide bases) DISSOCIATE into separate ions when dissolving occurs, leading to a greater concentration of dissolved particles. Therefore, given the same number of moles dissolved, IONIC compounds have GREATER colligative effects than do molecular substances (which do NOT break apart into atoms or ions).
We also illustrated that soluble salts (e.g. NaCl, KOH, (NH4)2SO4) are STRONG electrolytes, forming concentrated saturated solutions of CHARGED ions capable of conducting electricity.
Insoluble salts (e.g. PbCl2, AgBr, BaSO4) are WEAK electrolytes, forming DILUTE saturated solutions i.e. LOW concentrations of ions, which causes little to no electrical conductivity.
Molecular substances (EXCEPT for ACIDS- compound formulas that begin with "H", e.g. HCl) are NON-electrolytes. Thus, when molecules are dissolved in water, NO IONS form because covalent bonds are not broken via dissolving. So, solutions of molecular substances (e.g. CH3OH, C6H12O6, CH4, CO2, N2, Cl2) do NOT conduct electricity and do not have as large a colligative effect as do STRONG electrolytes.
Today, we discussed the mechanism of evolution via natural (or artificial) selection. We looked at two of four explicit examples of change/evolution of a species:
1. evolution of the modern-day long-neck giraffe from the ancestral shorter-neck giraffe
2. evolution of the peppered-moth population due to human-caused (artificial) environmental change (pollution)
Using the Darwinian explanation along with some modern understanding of genes/alleles, we showed how variation (via MUTATION, sexual reproduction, environmental influences) overpopulation, competition, SELECTION, and speciation/evolution can occur.
In the peppered-moth example, though a new species did not develop, there was a significant change in the percentage of moths with the light-color alleles; this is still an example of evolution within a population.
Chem 7/8- SOLUTIONS EXAM will be given on Wednesday!
we discussed colligative properties: boiling point ELEVATION, freezing point DEPRESSION, and vapor pressure lowering and noted that the greater the CONCENTRATION of DISSOLVED particles (ions OR molecules), the GREATER the colligative EFFECTS.
We then discussed how SOLUBLE ionic compounds (salts and hydroxide bases) DISSOCIATE into separate ions when dissolving occurs, leading to a greater concentration of dissolved particles. Therefore, given the same number of moles dissolved, IONIC compounds have GREATER colligative effects than do molecular substances (which do NOT break apart into atoms or ions).
We also illustrated that soluble salts (e.g. NaCl, KOH, (NH4)2SO4) are STRONG electrolytes, forming concentrated saturated solutions of CHARGED ions capable of conducting electricity.
Insoluble salts (e.g. PbCl2, AgBr, BaSO4) are WEAK electrolytes, forming DILUTE saturated solutions i.e. LOW concentrations of ions, which causes little to no electrical conductivity.
Molecular substances (EXCEPT for ACIDS- compound formulas that begin with "H", e.g. HCl) are NON-electrolytes. Thus, when molecules are dissolved in water, NO IONS form because covalent bonds are not broken via dissolving. So, solutions of molecular substances (e.g. CH3OH, C6H12O6, CH4, CO2, N2, Cl2) do NOT conduct electricity and do not have as large a colligative effect as do STRONG electrolytes.
We then discussed our precipitation lab.
Chem 9- SOLUTIONS EXAM will be given on Wednesday!
we discussed colligative properties: boiling point ELEVATION, freezing point DEPRESSION, and vapor pressure lowering and noted that the greater the CONCENTRATION of DISSOLVED particles (ions OR molecules), the GREATER the colligative EFFECTS.
We then discussed how SOLUBLE ionic compounds (salts and hydroxide bases) DISSOCIATE into separate ions when dissolving occurs, leading to a greater concentration of dissolved particles. Therefore, given the same number of moles dissolved, IONIC compounds have GREATER colligative effects than do molecular substances (which do NOT break apart into atoms or ions).
We also illustrated that soluble salts (e.g. NaCl, KOH, (NH4)2SO4) are STRONG electrolytes, forming concentrated saturated solutions of CHARGED ions capable of conducting electricity.
Insoluble salts (e.g. PbCl2, AgBr, BaSO4) are WEAK electrolytes, forming DILUTE saturated solutions i.e. LOW concentrations of ions, which causes little to no electrical conductivity.
Molecular substances (EXCEPT for ACIDS- compound formulas that begin with "H", e.g. HCl) are NON-electrolytes. Thus, when molecules are dissolved in water, NO IONS form because covalent bonds are not broken via dissolving. So, solutions of molecular substances (e.g. CH3OH, C6H12O6, CH4, CO2, N2, Cl2) do NOT conduct electricity and do not have as large a colligative effect as do STRONG electrolytes.
# posted by C @ 12:33 PM 
