3rd (global) exam of the 2nd term for 2nd ESO G
Name:
Date:
1. For the following atom, write the number of protons, the number of neutrons, the
number of electrons, the atomic number (Z), the mass number (A), the charge and say if
it is an anion, a cation or a neutral atom:
(0.6 points)
2. For the following atom, write the number of protons, the number of neutrons, the
number of electrons, the atomic number (Z), the mass number (A), the charge and say if
it is an anion, a cation or a neutral atom:
(0.6 points)
3. Complete the following table:
Number
Number
Number
Charge
Atomic
Mass
Anion,
of protons of
of
number
number
cation or
neutrons
electrons
(Z)
(A)
neutral
atom?
40
-2
91
50
36
29
24
38
+1
0
1
1
48
112
1
(2 points)
4. Balance the following chemical equation:
HCl + O2 → H2O + Cl2
(0.5 points)
5. Dinitrogen tetraoxide (N2O4) decomposes to form nitrogen dioxide (NO 2), according
to the following chemical equation, which is already balanced:
N2O4→2NO2
13
When 4.14∙10 molecules of N2O4 (41400000000000 molecules of N 2O4) decomposes,
how many molecules of NO2 are formed?
(0.5 points)
6. When carbon monoxide (CO) reacts with oxygen (O 2) we obtain carbon dioxide
(CO2), according to the following chemical equation, which is already balanced:
2CO + O2 → 2CO2
We know that 280 g of CO reacts with 160 g of O 2.What is the mass of CO2 that you are
going to obtain? What is the law that you are using?
(1 point)
7. Ammonia (NH3) and hydrochloric acid (HCl (aq)) react to form ammonium chloride
(NH4Cl), according to the following chemical equation, which is already balanced:
NH3 + HCl (aq) → NH4 Cl
We know that 68 g of NH3 react with 146 g of HCl to form 214 g of NH 4Cl.
If 34 g of NH 3 react:
a) What is the mass of HCl it has reacted with? What law have you used? (0.5 points)
b) What is the mass of NH 4Cl that has been obtained? What law have you used? (0.5
points)
8. What is the greenhouse effect? What are the environmental problems it causes? How
are humans creating this problem? (0.6 points)
9. Write the formula of the following compounds:
a) dinitrogen pentaoxide
b) gold (III) hydride
c) arsine
d) platinum (IV) oxide
e) bromic oxide (bromic anhydride)
f) hydrofluoric acid
g) calcium hydride
h) hydrogen selenide
(1.6 points)
10. Write the name of the following compounds in the nomenclature that is indicated (if
nothing is indicated, it means that we have only studied one way):
a) PbO (stock)
b) HBr
c) SO2 (traditional)
d) PH3
e) H2Te (aq)
f) Cu2O (stock)
g) MnH 2 (stock)
h) I2O7 (stoichiometric)
(1.6 points)
0.5 puntos extra:
Escribe en español el nombre de los compuestos 9a, 9b, 10c, 10d y 10e.
3rd (global) exam of the 2nd term for 2nd ESO G (answers)
Name:
Date:
1. For the following atom, write the number of protons, the number of neutrons, the
number of electrons, the atomic number (Z), the mass number (A), the charge and say if
it is an anion, a cation or a neutral atom:
3 protons, 4 neutrons, 3 electrons
(0.6 points)
atomic number (Z)=3, mass number (A)=7, charge=0
neutral atom
2. For the following atom, write the number of protons, the number of neutrons, the
number of electrons, the atomic number (Z), the mass number (A), the charge and say if
it is an anion, a cation or a neutral atom:
(0.6 points)
Atomic number (Z)=29, mass number (A)=64, charge=+2
29 protons, 35 neutrons, 27 electrons
cation
3. Complete the following table:
Number
Number
Number
Charge
Atomic
Mass
Anion,
of protons of
of
number
number
cation or
neutrons
electrons
(Z)
(A)
neutral
atom?
40
-2
91
51
42
40
anion
38
50
36
+2
38
88
cation
25
29
24
+1
25
54
cation
48
64
48
0
48
112
1
1
1
0
1
2
neutral
atom
neutral
atom
(2 points)
4. Balance the following chemical equation:
4HCl + O2 → 2H2O + 2Cl2
(0.5 points)
5. Dinitrogen tetraoxide (N2O4) decomposes to form nitrogen dioxide (NO 2), according
to the following chemical equation, which is already balanced:
N2O4→2NO2
13
When 4.14∙10 molecules of N2O4 (41400000000000 molecules of N 2O4) decomposes,
how many molecules of NO2 are formed?
(0.5 points)
6. When carbon monoxide (CO) reacts with oxygen (O 2) we obtain carbon dioxide
(CO2), according to the following chemical equation, which is already balanced:
2CO + O2 → 2CO2
We know that 280 g of CO reacts with 160 g of O 2.What is the mass of CO2 that you are
going to obtain? What is the law that you are using?
(1 point)
mreactants=mproducts
280+160=x
x=440 g=mCO2
LAW OF CONSERVATION OF MASS
7. Ammonia (NH3) and hydrochloric acid (HCl (aq)) react to form ammonium chloride
(NH4Cl), according to the following chemical equation, which is already balanced:
NH3 + HCl (aq) → NH4 Cl
We know that 68 g of NH3 react with 146 g of HCl to form 214 g of NH 4Cl.
If 34 g of NH 3 react:
a) What is the mass of HCl it has reacted with? What law have you used? (0.5 points)
I have used the law of definite proportions.
b) What is the mass of NH 4Cl that has been obtained? What law have you used? (0.5
points)
There are two ways of solving this problem:
1st way: using the law of definite proportions
2nd way: using the law of conservation of mass
mreactants=mproducts
→
34+73=x
→
x=107 g=mNH4Cl
8. What is the greenhouse effect? What are the environmental problems it causes? How
are humans creating this problem? (0.6 points)
Carbon dioxide (CO2) allows heat (from the sun) to enter in the Earth but doesn´t allow
it to go back to space. This effect is called greenhouse effect. Without greenhouse effect
the Earth would be too cold for us to live in it. But the increase of carbon dioxide
(caused by reactions of combustion; humans use these chemical reactions to obtain
energy) is causing an increase in greenhouse effect. Therefore more heat is retained in
the Earth and global temperature is going to rise. This is the global warming. Among
other damaging effects, the global warming is making the poles melt.
9. Write the formula of the following compounds:
a) dinitrogen pentaoxide
N2O5
b) gold (III) hydride
AuH3
c) arsine
AsH3
d) platinum (IV) oxide
PtO2
e) bromic oxide (bromic anhydride)
Br2O5
f) hydrofluoric acid
HF (aq)
g) calcium hydride
CaH2
h) hydrogen selenide
H2Se
(1.6 points)
10. Write the name of the following compounds in the nomenclature that is indicated (if
nothing is indicated, it means that we have only studied one way):
a) PbO (stock)
lead (II) oxide
b) HBr
hydrogen bromide
c) SO2 (traditional)
sulphurous oxide (sulphurous anhydride)
d) PH3
phosphine
e) H2Te (aq)
hydrotelluric acid
f) Cu2O (stock)
copper (I) oxide
g) MnH 2 (stock)
manganese (II) hydride
h) I2O7 (stoichiometric)
diiodine heptaoxide
(1.6 points)
0.5 puntos extra:
Escribe en español el nombre de los compuestos 9a, 9b, 10c, 10d y 10e.
9a: pentaóxido de dinitrógeno
9b: hidruro de oro (III)
10c: óxido sulfuroso (anhídrido sulfuroso)
10d: fosfina
10e: ácido telurhídrico