Intro chem lab exam 2 freezing point, hydrates, and nomenclature
Rule #1 for binary acids: If the polyatomic ion, and change its ending to:
"-ic acid"
What is the accepted literature value for the freezing point of acetic acid?
16.64 mp/degrees C
A student weighed a 4.7028g hydrated salt sample into a crucible. This sample weighed 3.8530g after heating to constant weight in the crucible. What was the percent water in the original hydrate sample?
4.7028-3.8530=0.8498 0.8498/4.7028 X 100 = 18.1% H2O
if copper(II) sulfate pentahydrate is known to be 36% water, how many grams of water will be lost when heating 5.75 grams sample?
5.75g X 36g/100g = 2.07g
rule #2 for oxyacids: Place a prefix in front of the acid name based on the number of oxygens the polyatomic ion contains
A) If the polyatomic ion has the same number of oxygens it normally had, do not add a prefix. B) If the polyatomic ion has fewer oxygens than it ordinarily contains, place the prefix "hypo-" in front of it. C) If the polyatomic ion has more oxygens than it ordinarily contains, place the prefix "per-" in front of it.
rule #1 for oxyacids: write the name of the most similar polyatomic ion, and change its ending.
A) if the polyatomic ion ends in"-ate" change its ending to "-ic acid" B) if the polyatomic ion ends in "-ite" change its ending to "-ous acid"
write a balanced equation of copper(II) sulfate pentahydrate.
CuSO4 + 5H2O <---> CuSO4 +5H2O
while writing an answer always remember
DETAILS!!!
Rule #2 for ionic compound nomenclature: place the anion name after the anion, and change its ending to "-ide".
If the anion is a polyatomic ion, do not change its ending.
when the hydrate was heated, could the decrease in mass be partly due to some substance other than water?
No. just the water. because the heat caused condensation which caused the liquid to form therefore only water left the substance
describe the appearance of te copper (II) sulfate pentahydrate after heating.
The blue copper turned grey/white in color
dependent variables are placed on which axis of the graph?
Y-axis
supercooling is when
a liquid goes below its freezing point without actually becoming a solid.
rule #2 for molecular compound nomenclature: write the name of the second element listed, and change its ending to "-ide".
add a prefix to indicate how many of this atom is present. Add a prefix for every number, including one
rule #1 for molecular compound nomenclature: write the name of the first element listed
add a prefix to indicate how many of this atom is present. Do not add a prefix if there is only one of this element!
energy must be added or removed from a solid to become a liquid?
added
dependent variables are variables that
change as a result of a change in the independent variable.
Independent variables are variables that
change at a predictable rate.
water of hydration or water of crystallization are
chemically combined with ions in the crystal.
Describe the appearance and odor of the substance obtained by heating copper(II) sulfate pentahydrate
clear liquid and is odorless
Hydrates are compounds that
contain water as an integral part of their solid structure.
In the context of this experiment, explain why icy roads are often treated with salt to make them safer to travel on. Is this an example of supercooling or freezing point depression?
freezing point depression. The salt is the solute and it lowers the freezing point of the ice.
Rule #1 for ionic compound nomenclature: Write the cation name first
if the cation has multiple charges, list it in roman numerals in parenthesis after the cation name
what is the difference between melting point and freezing point?
melting point is when a solid becomes a liquid and freezing point is when a liquid becomes a solid
"output" variables will
remain constant if the independent variable remains unchanged are dependent variables
energy must be added or removed from a liquid for it to become a solid?
removed
Rule #2 for binary acids Place the prefix "hydro-" in front of
the acid name
when the solid and liquid states are at equilibrium, which one has greater energy?
the liquid phase contains the greater amount of energy. Because in the liquid phase, even though particles are close to one another they can still move freely which give them more kinetic energy unlike solid particles which are fixed and have no kinetic energy.
Freezing point depression is when
the solvents freezing point decreases due to a solute being added
The freezing point of a substance is
the temperature at which it changes from a liquid to a solid.
The melting point of a substance is
the temperature at which it changes from a solid to a liquid
What do the freezing point and the melting point have in common?
they both change their state at these point. Ex. melting point is when a solid becomes a liquid. freezing point is when a liquid becomes a solid
remember, water is
water
Water molecules are referred to as
water of hydration or water of crystallization
independent variables are on which axis of the graph?
x-axis
