Wednesday, October 15, 2008

Stressed Out Words Of Support

Practice 7. Factors influencing friction solutions

STUDY OF THE FRICTION FORCE

Objective.

study the characteristics of the friction force with
surfaces. See whether or not depends on the contact surface,
weight and / or the characteristics of the materials that compose
.

Material.

- Dynamometer.

- Smooth surfaces of different materials.

- wooden blocks of different shapes.

theoretical basis

The frictional force is a force that always opposes motion
. In this case we study the frictional force between surfaces
. The friction force depends on the press a
body against another and the surface characteristics of contact
. The force that makes the object on the ground in a horizontal plane
equals weight in magnitude and opposite direction. In an inclined plane
this force is equal to P _n (
vertical component of weight). Normal is called ( N ) when
perpendicular to the surface. The other factor upon which the frictional force
is the coefficient of friction μ ,
which is determined by the characteristics
of surfaces and its value is experimentally since
depends on many factors such as roughness,
type of materials, surface defects ...

therefore the friction force is expressed by: Fr = μ • N
(Newton)

Notes μ is dimensionless.

operating method

Put the piece of wood supported by more
face on a given surface area.
then hooked the dynamometer to taco and put it horizontal.
Then we always pulling horizontally
dynamometer seeing what mark when it begins to move the whole
. Once you start moving, keep trying to pull
movement speed is uniform (v = constant) and we scored
marking the dynamometer. Make 3
measures and calculate the mean value.

repeat the same process with the lower part of the taco
surface.

repeat points 1 and 2 ° but
other contact surfaces.

then weighs the wooden block (the dynamometer
you better). With the calculated weight know what it is Normal (N).
then calculates for each measure the value of μ.

calculations and results and conclusions.

With the measurements obtained complete the following table:

Cara taco	M easure 1 (N)	M easure 2 (N)	M easure 3 (N)	M easure 4 (N)	Average	Normal (N)	coefficient μ
Mayor
Menor

issues and conclusions.

Does it depend on the friction force of the contact surface
? Explain it.

If the object moves faster, keeping constant
during the journey, "will depend somewhat
friction force being higher, lower or equal ?

By changing the type of surface contact, how the force varies
friction while the block is the same? Why
what?

If aumentásemos body mass, how
adjust the force of friction?

Can I Feel Wet Before Periods

Practice 7. Factors influencing friction

STUDY OF THE FRICTION FORCE

Objective.

study the characteristics of the friction force with
surfaces. See whether or not depends on the contact surface,
weight and / or characteristics of the materials that compose
.

Material.

- Dynamometer.

- Smooth surfaces of different materials.

- wooden blocks of different shapes.

theoretical basis

The frictional force is a force that always opposes motion
. In this case we study the frictional force between surfaces
. The friction force depends on the
pushes a body with another and the characteristics of
contact surfaces. The force that makes the object on the ground in a horizontal plane
equals weight in magnitude and opposite direction. In an inclined plane
this force is equal to P _n (
vertical component of weight). Normal is called ( N ) when
perpendicular to the surface. The other factor upon which the frictional force
is the coefficient of friction μ ,
which is determined by the characteristics of
surfaces and its experimental value, as dependent
many factors such as roughness, type of
materials surface defects ...

therefore the friction force is expressed by: Fr = μ • N
(Newton)

Note that μ is dimensionless.

operating method

Put the piece of wood supported by more
face on a given surface area. Then
block hooked to the dyno and put it horizontal.
Then we always pulling horizontally
dynamometer seeing what mark when it begins to move the whole
. Once you start moving, keep trying to pull
movement speed is uniform (v = constant) and we scored
marking the dynamometer. Make 3
measures and calculate the mean value.

repeat the same process with the lower part of the taco
surface.

repeat points 1 and 2 ° but
other contact surfaces.

then weighs the wooden block (the dynamometer
you better). With the calculated weight know what it is Normal (N).
then calculates for each measure μ value.

Calculations and results and conclusions.

With the measurements obtained complete the following table:

Cara taco	M easure 1 (N)	M easure 2 (N)	M easure 3 (N)	M easure 4 (N)	Average	Normal (N)	coefficient μ
Mayor
Menor

issues and conclusions.

Does it depend on the friction force of the contact surface
? Explain it.

If the object moves faster, keeping constant
during the journey, "will depend somewhat
friction force being higher, lower or the same?

By changing the type of surface contact, can vary
the force of friction while the block is the same? Why
what?

If aumentásemos body mass, how
adjust the force of friction?

Important Events Of Soccer

-1 º Bachillerato

PROBLEMS
Solutions

What
_{amount of ZnCl 2} needed to prepare
3L 0.32 M solution? Atomic masses: Zn = 65.3 u; Cl = 35.5 u.
Sun: 130.84 g.

7g is
KCl dissolved in 51g of water. What is the concentration of this solution
in% by mass? Sun:
12'07%.

How many grams of NaOH are there in 50cm 3 0'6M
dissolution of it? Na = 23U, H = 1u, O = 16U. Sun: 1'2g

is a solution prepared by mixing 90g water and 92g of ethyl alcohol
CH 3 CH 2 OH. Find:
a) proximate concentration of alcohol in water, b) moles of alcohol
c) molality of the solution if the alcohol is the solute
. Sun: 50'55%, 2 moles; 22'2 molal.

Calculate the grams of glucose (C 6 _{H 12 O} 6)
that must be dissolved in water 200g
to prepare a 0.2 molal solution. Sun: 7.2 g.

It has a nickel sulfate solution (II) to
6% by mass. Calculate the molarity of this solution
knowing its density is 1.06 g / mL. Ni = 58.5 u; S = 32U, O = 16U Sun: 0.41 M.

Calculate the molarity, normality, molality and mole fraction of solute
an aqueous solution
nitric acid to 33.50% by mass and density 1.2 g / mL. Sun: 6.38 M, 6.38 N, 8mm, 0.126.

have a solution _{2N H 2 S} density 0.95 g / mL. Halla
concentration: g / L, molarity,% by mass, molality
, Xs and Xd. Sun: 34g / L, 1M, 3.58%, 1.09 molal, 0.02 and 0.98.

Calculate the concentration in mass%
a solution of ethyl alcohol (CH 3 ₂ CH OH) in water, knowing that
Xs = 0.207. Atomic mass C = 12u, O = 16U, H = 1u.
Sun: 40%

We
5M solution of sodium sulfate and 250mL
want to prepare for another that is 75% and density 0.75 g / mL. a) What volume of solution
5M we take?; B) How
the prepare yourself? Na atomic mass = 23, S = 32 O = 16.
Sun: 198mL.

The
commercial sulfuric acid has a density of
1.84 g / mL and a concentration of 18.1 M. a) Calculate his wealth
in percent by mass; b) How many mL of the solution above
will be needed to prepare 2L
0.4 N solution? Sun: 96.4%, 22.1 mL.

colligative properties of solutions:

The radiator
a car contains 6L water and supplemented with 4kg
_{glycol CH 2 OH-CH} 2 OH (M = 62U).
want to know the temperature at which freeze the mixture. Kc = 1.86. Sun:
-20 º C.
A solution containing 4.5 g of a substance in water 125g
frozen at - 0.372 ° C. Calculated molecular mass of solute
. Kc = 1.86. Sun: 180u
Calculate the freezing temperature of a solution
produced by dissolving 10 g of sucrose (M = 342u) in 500 g of water.
Kc = 1.86. Sun:  0.11 º C
The
Nicotine is a compound of formula empirical
(C 5 H 7 N) n. Find its molecular formula
knowing that
dissolve 0.5 g of the substance in 12g of water, the resulting solution
boils at 100.14 ° C at normal pressure. Ke = 0.52. C = 12u, 14u
N =, H = 1u Sun: C ₁₀ _{H 14 N} 2.

mix is \u200b\u200b
^{150cm 3} of hydroxide solution 2M Sodium
with 50cm 3 other
0.5 M solution of the base. Follows the molarity of the resulting solution.
Sun: 1.625 M.

STOICHIOMETRY

In the combustion of 42

g carbon dioxide occurs. What volume in CN
oxygen and air are needed? What
amount of carbon dioxide is obtained?
Air has a 21% oxygen. Atomic weights C = 12u, O = 16U. Sun:
78.4 L of oxygen, air 373'3L; 154g CO 2 .

Al
heating potassium chlorate gets oxygen and potassium chloride
. a) Calculate the grams of potassium chlorate needed
for oxygen 2L in normal conditions;
c) How many grams of potassium chloride have been found?
d) What kind of reaction is? Data:
atomic mass-cas: Cl = 35'5u; K = 39u, O = 16U. Sun: b)
7'29 g of KClO 3 c) 4'43 g of KCl, d)
decomposition.

Find the volume of air that cn needed for combustion
total of 1 kg of coal for 84% of wealth in coal.
What volume of carbon dioxide at 127 º C and 760 mm pressure
has occurred? The air is 21% oxygen
. Sun: 7466.67 L air;
_{2296L CO 2}.

Halla
the purity of a sample containing ammonium sulfate, knowing that if taken
13'61 g and treated with excess caustic soda
3'82 liters of ammonia off
measured at 18 ° C and 745 mm of mercury. Atomic mass S = 32U;
O = 16U; N = 14u; H = 1u. Sun : 76%.

10g is
reacted aluminum oxide with excess hydrochloric acid and obtained
25g of aluminum chloride .
estimated yield of the reaction. Atomic masses: Al = 27U;
O = 16U and Cl = 35.5 u. Sun: 95.5%

The
reaction between sodium chloride and silver nitrate gives rise to chloride
silver and sodium nitrate. Assuming that the reaction takes place
a yield of 65% and we want to obtain 80.04 g
silver chloride, a) what
amount of sodium chloride is required? b) What if
sodium chloride were of a purity of 20%. M: atomic mass:
Na = 23U; Cl = 35'5u and Ag = 108u, Sun : a) 50'2
g NaCl, b) 251 g of sample

How many grams of sulfuric acid 90% of wealth
need to obtain 1 kg of calcium sulfate by reaction
with slaked lime Ca (OH ) ₂? S = 32U atomic masses,
Ca = 40U, H = O = 1U and 16U. Sun: 800'65 g.

Al
add calcium hydride occurs on water and calcium hydroxide
shows a gas. a) Write the reaction that takes place
. b) Calculate the grams of calcium hydride of 87% purity
that would be required for 2000 L of gas at 25 °
C and 720 mm Hg. M. atomic H = 1u, Ca = 40U. Sun: 1871.55 g
_{CaH 2}.

Calculate the grams of calcium carbide (CaC 2 ) that
can be obtained from calcium oxide, with 1000 g of carbon 90% of wealth
if the reaction yield is 70%.
What volume of carbon dioxide is obtained
CN? Atomic masses: C = 12u, Ca = 40U. Sun: 1344 g;
235.2 L.

Find
the volume of gaseous hydrochloric acid is
cn obtained by reacting with sulfuric acid
a sample of 500 g of salt formed in 30% potassium chloride and 70% of
sodium chloride. Data: atomic masses: Cl = 35'5u;
Na = 23U; K = 39u. Sun: 179.12 liters.

A 1g sample consisting of sodium carbonate and potassium carbonate
, treated with acid hydrochloric
get a mixture of 1.092 g sodium chloride and potassium chloride.
Calculate the initial mixture composition in per cent of each component
. Atomic masses: Na = 23U, C = 12u;
O = 16U; Cl = 35.5 u; K = 39u. Sun: 50% of each.

What
sulfuric acid may be obtained from 100g
pyrite. The reactions are unadjusted:
FeS 2 + O 2  Fe 2 _{O 3 + SO} 2, SO 2 _{+ O 2 } SO ₃;
_{SO 3 + H} 2 O  _{H 2 SO} 4.
atomic masses and Fe S = 32U = 56U. Sun : 163.3 g.

The hydrochloric acid
reacts with silver nitrate
forming silver chloride and nitric acid.
Calculate the grams of silver chloride to be formed if
react completely 25mL of hydrochloric acid solution 2M
. Atomic mass: Ag = 108u, Cl = 35.5 u.
Sun: 7.175 g.

reacted was 12 g calcium carbonate
with excess hydrochloric acid. Calculate: a) The volume of CO
2 at 20 ° C and 0.9 atmospheres.
b) The amount of calcium chloride obtained. c) The volume of HCl solution
16% by mass and density 1.25 g / mL
be used. d) What kind of reaction
belong? Data: atomic masses: Ca = 40U; O = 16U, C = 12u;
Cl = 35.5 u. Sun: a) 3'2 l; b) 13'32 g.
c) 43.8 mL.

For
reaction of zinc with AC. hydrochloric
get zinc and hydrogen chloride. a) What kind of reaction
is it? b) What volume of hydrochloric acid
55% by mass and density 1.5 g / mL,
must react with an excess of zinc to produce
50L of hydrogen, measured at 32 º C and 760mm Hg. Atomic masses:
S = 32U; O = 16U, H = 1u. Sun: 177 mL

In
a flask of 1 liter of oxygen is 0.05 moles and 0.05 moles of hydrogen
. A spark is produced
and liquid water. Calculate: a) The moles of water formed, b)
How many moles of gas remain without reacting? c) What
is the pressure inside the flask at 0 ° C? d) Indicates the type of reaction
. Sun:
a) 0.05 moles of water; b) 0.025 moles; c) 0'56
atmospheres.

is reacted a mixture of 48g of S and 78.4 g of Fe to produce iron sulfide
(II) Indicates a) Is there any
excess reagent?, b) How many grams of ferrous sulphide will
? Atomic mass data S = 32U; Fe = 56U. Sun :
a) Excess of 3.2 g of sulfur., B) 123'2 g FeS.

burning desire is
78.4 L of methane gas CH 4 CN, using 200g
oxygen. The reaction produces carbon dioxide and water
. A) Which reactant is in excess moles
and how many left? B) Calculate the grams of carbon dioxide
to be obtained. Atomic masses: C = 12u;
O = 16U. Sun: 137.5 g 0.375 moles

burn Al
0'42 g of an oil is produced _{1'32 g of CO 2}
and 0,54 g water. If the density relative to air is 1.45, calculated
molecular formula. (Hint:
average molecular mass of air = 28'8 u) (Sun: C _{3 H} 6)

In the fuel
n of 0'785 g
an organic compound formed by C, H and O, are obtained _{1'5g CO 2 and}
0'921 g of water. To vaporize 0'206 g of compound 108 is evicted
mL of air measured over water at 14 º C and 756 mm Hg
. Find the molecular formula of the compound. (Hint:
vapor pressure of water at 14 º C is 12 mm Hg) (Sol (C H 2 O 6).

By analyzing an organic compound results:
40'7% C; 5.1% and 54'2% H O.
solution formed by 11.8 g of compost and 200 mL of water freezes at 93 º C.
-0 Find its molecular formula. (Soln: 4
C 6 H _O 4)

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Wednesday, October 8, 2008

Leukoplakia Of The Tongue

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