Answer:
C.ratio of elements in the compound.
Explanation:
A compound is a substance that constitutes two or more elements in a defined proportion. A chemical compound is different from another compound in what it contains i.e. elements. A chemical formula shows the elements contained in a specific compound. For example, the chemical formula of sodium chloride (NaCl) shows us that it contains Sodium (Na) and Chlorine (Cl) elements as represented by symbols.
In addition to this, a chemical formula also shows the ratio of each element that makes up the compound. An element can have more than one atom in a compound. For example, CaCl2 is the chemical formula for Calcium chloride and it shows is that the ratio of Calcium (Ca) to Chlorine (Cl) is 1:2.
Answer:
49.09 moles of gas are added to the container
Explanation:
Step 1: Data given
Initial volume = 3.10 L
Number of moles gas = 9.51 moles
The final volume = 19.1 L
The pressure, temperature remain constant
Step 2: Calculate number of moles gas
V1/n1 = V2/n2
⇒with V1 = the initial volume of the gas = 3.10 L
⇒with n1 = the initial number of moles = 9.51 moles
⇒with V2 = the increased volume = 19.1 L
⇒with n2 = the final number of moles gas
3.10L / 9.51 moles = 19.1 L / n2
n2 = 58.6 moles
The new number of moles is 58.6
Step 3: calculate the number of moles gas added
Δn = 58.6 - 9.51 = 49.09 moles
49.09 moles of gas are added to the container
Answer:
Mass of benzene is: 149.3 g
Explanation:
Let's use density to calculate mass.
Density = Mass / Volume
Mass = Density . volume
Be careful, because density is in g/mL and the volume is in L. So let's convert the L to mL: 0.170 L . 1000 mL / 1L = 170 mL
0.8787 g/mL . 170 mL = Mass of benzene
Mass of benzene is: 149.3 g
Answer: The best way to promote the process are:
--> Add a bit of solid as a seed crystal.
--> Scratch the bottom of the flask gently with a stirring rod.
Explanation:
A crystal growth is seen is SUPERSATURATED solutions which contains more solute than it can normally dissolve at that given temperature. It is usually very UNSTABLE and capable of releasing the excess solute if disturbed, either by shaking or seeding with a tiny crystals.
Crystallization can be used for the separation of two salts with different solubilities as well as for purification of a soluble salt that contains insoluble solid impurities. Recrystallization improves the validity of the process. Crystallization can be initiated by:
--> Scratching the bottom of the flask gently with a stirring rod: scratching initiates crystallization by providing energy from the high-frequency vibrations.
--> Adding a bit of solid as a seed crystal: Seed crystals create a nucleation site where crystals can begin growth.
Answer:
- Nitrogen has four pairs of electrons: 3 bonds and 1 lone pair in the valence shell;
- Electrons repel one another based on the VSEPR theory;
- Nitrogen has a total of 7 protons (its atomic number is 7) in its nucleus.
Explanation:
The shape and the bond orientation of molecules and ions are both explained by the valences shell electron pair repulsion theory (VSEPR).
Ammonia, 
, is a molecule which contains three N-H bonds, as well as one lone pair on nitrogen. According to the VSEPR theory, molecules try to acquire a shape which would minimize the repulsion exhibited by the electron clouds present, that is, between the bonding (shared in a bond) and non-bonding (lone pair) electrons.
In VSEPR, our main step is to calculate the steric number, this is the sum of the number of bonds (ignoring the multiplicity of any bond) and the lone pairs on a central atom. In ammonia, we have 3 bonds and 1 lone pair, totaling to a steric number of 4. A steric number of 4 without any lone pairs on a central atom and just bonds would yield a tetrahedral shape with bond angles of 
.
Now, in this case, since we have a lone pair instead of a bond, it is repelling stronger decreasing the bond angles to about 
.
The greater the number of lone pairs, the lower the angle becomes.
To summarize:
- Nitrogen has four pairs of electrons: 3 bonds and 1 lone pair in the valence shell;
- Electrons repel one another based on the VSEPR theory;
- Nitrogen has a total of 7 protons (its atomic number is 7) in its nucleus.
