Chemical changes cause a substance to change into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions. The “ingredients” of a reaction are called reactants, and the end results are called products.
The heat will flow from copper to aluminum because Cu is at higher temperature. The heat liberated is -7.60kJ
When two metals at different temperatures are kept in contact, heat flows from hotter metal to colder metal until thermal equilibrium is reached.
Here Copper is at a temperature of 60 degree Celsius and aluminum is at 40 degree Celsius. Thus, heat will flow from Cu to Al.
In order to calculate the amount of heat liberated following calculations are required.
m1=262 g
T1=87 oC
Cp=0.385 J/g oC
T2=11.8 oC
The heat liberated can be expressed as follows:
Q=mCp(T2-T1)
Q=262 g*0.385 J/goC(11.8-87)oC
Q=-7585 J
=-7.60kJ
To learn more about heat check the link below:
brainly.com/question/13439286
#SPJ4
Answer:
The correct answer is:
<em>(1) It is important that the sample is dissolved in just enough hot solvent. </em>
Explanation:
The process of recrystallization is important to eliminate the impurities and to obtain better crystals of the solid. The solvent used to perform the recrystallization must have a high dissolution power of the substance to be recrystallized and a low dissolution power of the impurities. This is in order to eliminate most impurities. Furthermore, <em>It is important that the sample is dissolved in just enough hot solvent </em>because this should be easy to remove after the recrystallization and the crystal should form easily when the solution cools. Also, it is better to add the hot solvent to solubilize the crystals and keep the impurities insoluble, instead of adding the cold solvent and heating the solution. Additionally, the process of cooling the solution must be done slowly to obtain large and fewer crystals. A fast ice-cooling will form smaller crystals.
Blocks on the periodic table will not list a mass number of elements in this scenario.
<h3>What is Periodic table?</h3>
This table comprises of elements in order of their atomic number which determines their chemical properties.
It contains the atomic number but however doesn't contain the mass number of the elements.
Read more about Periodic table here brainly.com/question/15987580
#SPJ12
