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 can look at the polarity of the substances. Polarity refers to the distribution of electron density in a molecule or compound.
Water is a polar molecule, which means it has a slightly positive end (hydrogen atoms) and a slightly negative end (oxygen atom). Polar substances have an unequal distribution of charge and can form hydrogen bonds with water molecules, making them more likely to dissolve in water.
Now let's go through each substance and determine if it will dissolve significantly in water based on its polarity:
a) CH4 (methane) - Methane is a nonpolar molecule because it consists of only carbon and hydrogen atoms. Nonpolar molecules do not have an uneven distribution of charge and, therefore, do not readily dissolve in water. So, CH4 does not dissolve significantly in water.
b) KCl (potassium chloride) - KCl is an ionic compound composed of potassium cations (K+) and chloride anions (Cl-). Ionic compounds, such as KCl, are usually highly soluble in water because the positive and negative ions can separate and interact with the polar water molecules. Therefore, KCl dissolves significantly in water.
c) He (helium) - Helium is a noble gas and consists of individual atoms. Noble gases are nonpolar because they have a symmetrical distribution of electrons around the nucleus. As a result, helium does not form significant interactions with water molecules, and it does not dissolve significantly in water.
d) MgSO4 (magnesium sulfate) - Magnesium sulfate is an ionic compound similar to KCl. It contains magnesium cations (Mg2+) and sulfate anions (SO42-). As with other ionic compounds, magnesium sulfate is highly soluble in water due to the strong interaction between its ions and polar water molecules. Therefore, MgSO4 dissolves significantly in water.
e) Sucrose - Sucrose (table sugar) is a polar compound because it consists of multiple atoms with different electronegativities. Polar substances like sucrose can form hydrogen bonds with water molecules, allowing them to dissolve readily in water. So, sucrose dissolves significantly in water.
f) NaHCO3 (sodium bicarbonate) - Sodium bicarbonate is also an ionic compound, containing sodium cations (Na+) and bicarbonate anions (HCO3-). As mentioned earlier, ionic compounds tend to be highly soluble in water due to the attraction between their ions and water molecules. Therefore, NaHCO3 dissolves significantly in water.
In summary, the substances that dissolve significantly in water due to their polarity are KCl, MgSO4, sucrose, and NaHCO3. Meanwhile, CH4 and He do not dissolve significantly in water because they are nonpolar substances.