Molecules i àtoms

Classified in Chemistry

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1. Match the symbol on the left with its appropriate description on the right. 
d →               (a) A precipitate forms. 
a ↓                 (b) A gas forms. 
b ↑                (c) A reversible reaction occurs.
f (l)                (d) Heat is applied to the reactants. 
e (aq)            (e) A chemical is dissolved in water. 
c ←→            (f ) A chemical is in the liquid state. 

3. In each of the following formulas, write the total number of atoms present. 
12 atoms                  a. 4SO>2 
6 atoms                    b. 8O>2 
51 atoms                  c. 3Al>2(SO4)>3 
3x10^24 atoms        d. 6x10^23 HNO3 

1. Match the equation type on the left to its representation on the right. 
c synthesis                         (a) AX BY → AY BX 
d decomposition               (b) A BX → AX B 
b single-displacement       (c) A B → AX 
a double-displacement     (d) AX → A X

5. Identify the products when the following substances decompose: 
its separate elements                      a. A binary compound 
metal oxide + water                        b. Most metal hydroxides 
metal oxide + carbon dioxide         c. A metal carbonate 
water + sulfur dioxide                     d. The acid H2SO3

3. In each of the following pairs, identify the more active element. 
F2    a. F2 and I2                     K        b. Mn and K                   H      c. Cu and H

2. A. What is meant by ideal conditions relative to stoichiometric calculations? 
The limiting reactant is completely converted to product with no losses, as Dictated by the ratio of coefficients. 
b. What function do ideal stoichiometric calculations serve? 
They determine the theoretical yield of the products of the reaction. 
c. Are actual yields typically larger or smaller than theoretical yields? 
smaller

1. C The average speed of a gas molecule is most directly related to the 
(c) temperature of the gas.

3. B Which of the following statements about liquids and gases is not true? 
(b) Molecules in a liquid can vibrate and rotate, but they are bound in fixed positions.

4. Answer solid or liquid to the following questions: 
solid     a. Which is less compressible?
liquid    b. Which is quicker to diffuse into neighboring media? 
solid     c. Which has a definite volume and shape? 
solid     d. Which has molecules that are rotating or vibrating primarily in place?

5. Explain why almost all solids are denser than their liquid states by describing what is occurring at The molecular level.
In solids, particles are more closely packed than in liquids, due to stronger attractive Forces between the particles of the solid. 

6. A general equilibrium equation for boiling is 
liquid + energy ←→vapor 
forward reaction    a. The temperature of the system is increased. 
reverse reaction     b. More molecules of the vapor are added to the system. 
reverse reaction     c. The pressure on the system is increased.

a. Explain briefly why the pressure decreases as the altitude increases. 
As the altitude increases, there are fewer gas molecules above; therefore, there Are fewer gas molecules to exert their pressure. 
b. A few places on Earth are below sea level (the Dead Sea, for example). What would be true About the average atmospheric pressure there?
It would exceed 100 kPa at places below sea level

1. A A saturated organic compound 
(a) contains all single bonds. 

2. Arrange the following in order of increasing boiling point: 
1 a. Ethane    2 b. Pentane    3 c. Heptadecane 

3. Recall that isomers in organic chemistry have identical molecular formulas but different structures And IUPAC names. 
True    a. Two isomers must have the same molar mass. True or False? 
False    b. Two isomers must have the same boiling point. True or False? 

4. Explain why hydrocarbons with only single bonds cannot form geometric isomers. 
The free rotation around the single bonds between carbon atoms prevents molecules With the same sequence of atoms from having different orientations in space.

8. Match the general formula on the right to the corresponding family name on the left.
e carboxylic acid    h ester    d alcohol    c ether
A alkyl halide     F amine     B aldehyde     g ketone

1. Use carbohydrate(s), lipid(s), protein(s), or DNA to complete the following statements.
a. DNA is the largest molecule found in cells. 
b. Lipids are the major component in a cell membrane. 
c. Carbohydrates provides most of the energy that is available in plant-derived food. 
d. Protein gets its name from the Greek word meaning “of first importance.” 

6. A segment of RNA has the base sequence UAG CCU AAG CGA UAC GGC ACG.
 a. What is the base sequence in a complementary strand of RNA?
AUC GGA UUC GCU AUG CCG UGC
 b. What is the base sequence in the complementary strand of DNA?
ATC GGA TTC GCT ATG CCG TGC

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