Which of the following substances dissolve to a significant extent in water? Explain your answer in terms of polarity.
a) CH4 b) KCL c)He d)MgSO4 e)sucrose f)NaHCO3
To determine which substances dissolve to a significant extent in water, we need to consider the concept of polarity.
Polarity refers to the separation of electric charge within a molecule, which creates partial positive and partial negative charges. Water (H2O) is a polar molecule, which means it has areas of partial positive charge (hydrogen atoms) and areas of partial negative charge (oxygen atom).
Now, let's analyze each substance:
a) CH4 (methane): CH4 is a nonpolar molecule as it consists of four nonpolar C-H bonds. Nonpolar substances do not dissolve well in water because the partial positive and partial negative charges in water cannot effectively interact with the nonpolar molecules, resulting in low solubility. Therefore, CH4 does not dissolve to a significant extent in water.
b) KCl (potassium chloride): KCl is an ionic compound consisting of a metal (K) and a nonmetal (Cl). Ionic compounds, such as KCl, dissolve well in water due to the attraction between the polar water molecules and the charged ions. The partial positive charge of water attracts the negatively charged Cl- ion, and the partial negative charge attracts the positively charged K+ ion. Therefore, KCl dissolves to a significant extent in water.
c) He (helium): He is a noble gas and consists of individual atoms. Noble gases like helium are nonpolar and do not dissolve in water. They lack the partial charges required to interact with polar water molecules. Hence, He does not dissolve to a significant extent in water.
d) MgSO4 (magnesium sulfate): MgSO4 is an ionic compound similar to KCl. As mentioned before, ionic compounds dissolve well in water. The polar water molecules attract and surround the positive Mg2+ ions and the negative SO4 2- ions, causing MgSO4 to dissolve to a significant extent in water.
e) Sucrose: Sucrose (C12H22O11) is a polar molecule due to the presence of polar O-H and C-O bonds. The partial positive and partial negative charges in sucrose can interact with the charges in water molecules through hydrogen bonding, enabling it to dissolve to a significant extent in water.
f) NaHCO3 (sodium bicarbonate): NaHCO3 is an ionic compound that includes both a metal (Na) and polyatomic ions (HCO3-). Similar to KCl and MgSO4, NaHCO3 dissolves well in water due to the interaction between the polar water molecules and the charged ions.
In summary, substances with ionic or polar bonds (KCl, MgSO4, sucrose, NaHCO3) dissolve to a significant extent in water due to the effective interaction between polar charges. Nonpolar compounds (CH4, He) do not dissolve well in water because they lack the necessary partial charges to interact with the polar water molecules.
Of the substances listed, the ones that dissolve to a significant extent in water are KCl, MgSO4, sucrose, and NaHCO3.
Water is a polar molecule, meaning it has a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. This polarity allows water molecules to interact with other charged or polar molecules.
KCl (Potassium chloride) is an ionic compound composed of potassium cations (K+) and chloride anions (Cl-). In water, the positive ends of the water molecules are attracted to the negatively charged chloride ions, and the negative ends of the water molecules are attracted to the positively charged potassium ions, helping to break apart the solid and dissolve it into the water.
MgSO4 (Magnesium sulfate) is also an ionic compound composed of magnesium cations (Mg2+) and sulfate anions (SO4^2-). Similar to KCl, the positive ends of water molecules are attracted to the negatively charged sulfate ions, and the negative ends of water molecules are attracted to the positively charged magnesium ions, aiding in the dissolution of the compound.
Sucrose (C12H22O11), commonly known as table sugar, is a polar molecule due to the presence of hydroxyl groups (-OH) and oxygen atoms. The positive ends of water molecules can form hydrogen bonds with the hydroxyl groups and oxygen atoms in sucrose, allowing it to dissolve in water.
NaHCO3 (Sodium bicarbonate), also known as baking soda, is a soluble compound composed of sodium cations (Na+) and bicarbonate anions (HCO3-). The positive ends of water molecules are attracted to the negatively charged bicarbonate ions, while the negative ends of water molecules are attracted to the positively charged sodium ions, facilitating its dissolution in water.
On the other hand, substances such as CH4 (methane) and He (helium) are nonpolar molecules. Nonpolar molecules do not have significant charges and do not readily form interactions with polar water molecules. Therefore, CH4 and He do not dissolve to a significant extent in water.
Like dissolves like.
Polar solutes will generally dissolve in water as well as those materials containing OH groups. You can take it from there.