1. Pure substance x is solid at room temperature. if the substance is heated to 230 C 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!
The substance X is a compound because the boiling point of the substance is very high, this possibility is an ionic compound. when frozen at room temperature is around 25 degrees centigrade the substance can not be frozen, because freezing of these compounds are also very high
b. Does it chemical change occured? if so can it be said undergo an endotherm changing, based on the information provided?
yes it can be said of any change in the chemical reaction. because the form of substances and automatically change the atomic structure inside will also change. can also be said that the endothermic reaction occurs because the endothermic reaction heat transfer occurs from the environment to the system or to the reaction heat is needed.
c.can it be said that the liquid is an element, based on the information provided
can be said that the fluid is due as a result of the decomposition element X compound which has been heated
2. When a candle that weighs 10 g is burned in oxigen, carbon dioxide and water vapor formed by combustion the weight more than 10 g. was this case match with the law of conservation of mass. Explain it!
in the event the law does not apply because the system is open to allow for substances other substances to catch fire, causing the mass of a substance produced from the burning candle wax is greater than the mass of the candle
3. When carbon burns in oxygen under limited number, it will form two gaseous compounds. Suggest the way to diffrerentiate the two compounds with one another.
when the carbon was burned then there are two potential outcomes, namely carbon monoxide and carbon dioxide. Carbon monoxide is produced from incomplete combustion of carbon compounds, often occur in internal combustion engines. Carbon monoxide is formed when there is a lack of oxygen in the combustion process. by because it will have a black soot
while the carbon dioxide so that complete combustion occurs because there are no byproducts such as soot
while the carbon dioxide so that complete combustion occurs because there are no byproducts such as soot
4. after mendeev compiled the periodic table, he concluded that the atomic weights of certain elements was wrong ruling, and this conclusion was apparently correct. How mendeelev was able to predict the several atomic weights were wrong? why his predictions are not always right. Explain it!
Dmitry Ivanovich concluded that the properties of elements are periodic function of the relative atomic mass. That is, if the elements disusunmenurut relative atomic mass increases, then the specific properties will be repeated periodically. Mendeleev placed elements that have a similarity of traits in a vertical column called class. Mendeleev mengkosongkan some places. This was done to establish the similarity of the properties in the class. For example, placing Mendelev Ti (Ar = 48) in group IV and group III left empty because Ti is more similar to C and Si, than with B and Al. Mendeleev predicted the properties of the elements that have not known it. The forecast is based on the known properties unsurlain, adjacent either horizontally or upright. When the elements are predicted was found, teryata are highly in accordance with predictions Mendeleev. One example is a germanium (Ge), which was found in 1886, which by Mendeleev named ekasilikon. The weakness of this theory is still contained elements of a larger mass is located in front of the element whose mass is smaller. Co: Tellurium (te) = 128 in kiriIodin (I) = 127. this is because the elements that have properties kemirpan placed in one class. The weakness of this theory is the atomic mass pemebetulan. Previous atomic mass. In previous atomic mass = 76 to 113. besides Be, from 13.5 to 9. N from 120 to 240.
5. When an aqueous solution of merkuri chloride is added an aqueous solution of silver nitrate, a white solid forms. Identify the white solid and write the balanced equation for the reaction that occurs
HgCl2 + 2AgNO3 ---> Hg (NO3) 2 + 2AgCl
The resulting white powder is silver nitrate.
