MID TEST
UTS
1.
Pure substance X is solid at room temperature.
If the subtance is heated to 2300C is melted gradually. If then
cooled to room temperature, the liquid can not be frozen.
a.
Is it possible X of an element or a compound.
Explain it !
b.
Does it a chemical change occured ? If so can it
be said to undergo an endotherm changing, based on the information provided ?
c.
Can it be said that the liquid is an element,
based on the information provided.
2.
When a candle that weighs 10g is burned in
oxygen, carbon dioxide and water vapor formed by combustion the weight more
than 10g. Was this case match with the law of conservation of mass. Explain it
!
3.
When carbon burns in oxygen under limited
number, it will form two gaseous compounds. Suggest the way to differentiate
the two compounds with one another.
4.
After mendeev compiled the periodic table, he
concluded that the atomic weights of certain elements was wrong ruling, and
conclusion was apparently correct. How mendeleev was able to predict that
several atomic weights were wrong ? why his predictions are not always right.
Explain !
5.
When an equeous solution of merkuri chloride is
added to an aqueous solution of silver nitrate, a white solid forms. Identify
the white solid and write the balanced equation for the reaction that occurs.
Answer :
1. A. X
is an element because
X is not a mixture of various other
substances.
B. Able, because of a transfer of heat energy from the environment kesistem trial
C. Yes, can it
B. Able, because of a transfer of heat energy from the environment kesistem trial
C. Yes, can it
2. The law
of conservation of mass is, the
mole before and after the reaction is the same, while
the weight of the wax is not the same because of added oxygen, the weight
of the combustion is more severe than ever. It
can be concluded that no relation
to the law of conservation of
mass, because the initial weight
and ultimately different.
3. By way through
a chemical reaction, comparing the components that make up the compound.
4. Here Mendeleev predicted that the period 1 + 3 = 2
Example : 19K +
55CS = 37 (RB)
2
5.2Hg Cl + Ag (NO3)2 Ag Cl2 + 2Hg NO3 
a white solid
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