1. 1.
pure substance x is solid at room temperature.
if the substance 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 endoterm changing, based on the information provided?
c.
Can it be said that the liquid is an element,
based on the information provided.
ANSWER :
A. I think it is an element x as an element is a pure substance at room temperature (25 C) can be gaseous, liquid, or solid. element x can not be frozen because the element can not be converted into shape after being given a treatment like sipanaskan, if only by ordinary chemical methods.
B. Not because of a chemical change is a change in a substance that produces a new substance. whereas the treatment of these elements are not generated new substance, after heating that occurs is a change in form only. not create a new substance.
The characteristics that indicate a chemical change:
discoloration
Changes in odor
the formation of gas
The emergence of light
The formation of new sediment
The characteristics that indicate a chemical change:
discoloration
Changes in odor
the formation of gas
The emergence of light
The formation of new sediment
Changes in pH.
C. Yes
1. 2. When a candle that weight 10 gr is burned in
oxygen, carbon dioxide and water vapor formed by combustion the weight more
than 10 gr. Was this case match whit the law of mass. Explain it.
ANSWER :
At this candle burning reaction occurs in a closed system which means the energy is not out of the system, so that the mass of the system will not change. according to the law of conservation of mass, the weight of the candle after burning is not possible increases or decreases because of the mass of substances before and after it is treated the same. Violations of the law of conservation
mass can only occur in an open system with a process that involves significant energy changes as nuclear reactions.
mass can only occur in an open system with a process that involves significant energy changes as nuclear reactions.
3
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.
ANSWER :
when carbon burns oxygen then produced two compounds, namely CO2 and CO. Carbon monoxide, chemical formula CO, is a colorless gas, odorless, and tasteless. It consists of one carbon atom covalently bonded to one oxygen atom. In this bond, there are two covalent and one coordinate covalent bonds between carbon and oxygen atoms. while carbon dioxide (CO2) is a substance carbonic acid is
type of chemical compound composed of two oxygen atoms covalently bonded to a carbon atom. He is a gas at standard temperature and pressure conditions, and is present in the Earth's atmosphere. The average concentration of carbon dioxide in Earth's atmosphere roughly 387 parts per million by volume [1] though this number may vary depending on location and time. Carbon dioxide is an important greenhouse gas because it absorbs infrared light strongly.
I tell is to soak each compound with lime. the carbon dioxide will be formed precipitate is CaCO3, while the carbon dioxide is not the case deposition.
type of chemical compound composed of two oxygen atoms covalently bonded to a carbon atom. He is a gas at standard temperature and pressure conditions, and is present in the Earth's atmosphere. The average concentration of carbon dioxide in Earth's atmosphere roughly 387 parts per million by volume [1] though this number may vary depending on location and time. Carbon dioxide is an important greenhouse gas because it absorbs infrared light strongly.
I tell is to soak each compound with lime. the carbon dioxide will be formed precipitate is CaCO3, while the carbon dioxide is not the case deposition.
1 4.
After mendeev compiled theperiodic table, he
conclude that the atomic weight of certain elements was wrong ruling, and this
conclusion was apparently correct. How Mendeleev was able to predict that
several atomic weight were wrong? Why his predictions are not always right.
Explain!
ANSWER :
because Mendeleev arrange the elements of the periodic system by placing the elements in the form of rows and columns. elements in the same pool has properties mirimp. he said contained the following elements called eka aluminum - aluminum with the symbol Ea. properties of elements can be predicted based on comparison to neighboring elements. whereas in 1874, the French chemist, Paul Emile Lecoq de Bois-Baudran find Gallium element that has properties similar to eka-aluminum predicted by mendeelev. as for making predictions Mendeleev one is:
1) The length of the period is not the same and why not described.
2) Some elements are not ordered by their atomic mass increases, for example: Te (128) before I (127).
3) the mass difference of successive elements are not always 2, but the range between 1 and 4 so difficult to predict the mass of an element that has not been known.
4) Valence more than one element of the unpredictable group.
5) anomaly (deviation) elemental hydrogen from other elements not described.
1) The length of the period is not the same and why not described.
2) Some elements are not ordered by their atomic mass increases, for example: Te (128) before I (127).
3) the mass difference of successive elements are not always 2, but the range between 1 and 4 so difficult to predict the mass of an element that has not been known.
4) Valence more than one element of the unpredictable group.
5) anomaly (deviation) elemental hydrogen from other elements not described.
1.
5. When an aqueous solution of mekuri 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 :
2HgCl +2AgNO3 -----> 2AgCl+ Hg(NO3)2
The resulting white solid was 2AgCl.
