Question

(1) \(\mathrm{SiO}_{2}+\mathrm{NaOH} \rightarrow ?\) (2) \(\mathrm{SiO}_{2}+\mathrm{HF} \rightarrow ?\) The products of \((2) \&(1)\) respectively are (a) \(\mathrm{SiF}_{4}, \mathrm{Na}_{2} \mathrm{SiO}_{3}\) (b) \(\mathrm{H}_{2} \mathrm{SiF}_{6}, \mathrm{SiO}_{4}{ }^{4-}\) (c) \(\mathrm{Na}_{2} \mathrm{SiO}_{4}, \mathrm{H}_{2} \mathrm{SiF}_{6}\) (d) \(\mathrm{Na}_{2} \mathrm{SiO}_{3}, \mathrm{SiF}_{4}\)

Short answer

The correct option is (c) \( \text{Na}_2\text{SiO}_3, \text{H}_2\text{SiF}_6 \).

Step-by-step solution

Identify the Reaction with NaOH

The reaction of silicon dioxide, \( \text{SiO}_2 \), with sodium hydroxide, \( \text{NaOH} \), forms sodium silicate, which is a compound containing \( \text{Na}_2\text{SiO}_3 \). The balanced chemical equation for this reaction is: \( \text{SiO}_2 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SiO}_3 + \text{H}_2\text{O} \). Thus, when \( \text{SiO}_2 \) reacts with \( \text{NaOH} \), the product is \( \text{Na}_2\text{SiO}_3 \).

Identify the Reaction with HF

Now, consider the reaction when silicon dioxide, \( \text{SiO}_2 \), reacts with hydrofluoric acid, \( \text{HF} \). This reaction forms hexafluorosilicic acid, \( \text{H}_2\text{SiF}_6 \). The balanced equation for this reaction is: \( \text{SiO}_2 + 6\text{HF} \rightarrow \text{H}_2\text{SiF}_6 + 2\text{H}_2\text{O} \). Thus, the product of this reaction is \( \text{H}_2\text{SiF}_6 \).

Match the Products to Given Options

From the reactions determined: (1) yields \( \text{Na}_2\text{SiO}_3 \) with \( \text{NaOH} \) and (2) yields \( \text{H}_2\text{SiF}_6 \) with \( \text{HF} \). Comparing these products with the options available, the correct match is option (c) \( \text{Na}_2\text{SiO}_3, \text{H}_2\text{SiF}_6 \).

Key concepts

Inorganic Chemistry

Inorganic Chemistry is a vast branch of chemistry dealing with inorganic compounds, primarily focusing on compounds that do not feature carbon-hydrogen bonds unlike organic chemistry. This field encompasses a diverse range of substances such as metals, minerals, and organometallic compounds. Silicon dioxide (\(\text{SiO}_2\)) and sodium hydroxide (\(\text{NaOH}\)) are classic examples of inorganic compounds.

Silicon dioxide is the second most abundant element in the Earth's crust and is known for forming minerals such as quartz. Interestingly, it reacts with strongly basic substances like \(\text{NaOH}\) to form sodium silicate (\(\text{Na}_2\text{SiO}_3\)). This type of chemical transformation highlights key concepts in inorganic chemistry such as the formation of salts and the reactions between a strong base and acidic oxide.

On the other hand, hydrofluoric acid (\(\text{HF}\)) is used in this exercise to showcase its reactivity with silicon dioxide. This interaction results in the formation of hexafluorosilicic acid (\(\text{H}_2\text{SiF}_6\)), demonstrating the formation of an inorganic acid through a reaction involving a non-metallic oxide. These kinds of reactions are fundamental in understanding the transformation of inorganic chemicals.

Acid-Base Reactions

Acid-Base Reactions involve the transfer of hydrogen ions between the reactants, leading to the formation of water and a salt. They are a significant aspect of many chemical processes. In the exercise provided, you encounter two different types of acid-base reactions involving silicon dioxide.

• The reaction between \(\text{SiO}_2\) and \(\text{NaOH}\) fits the model of an acid-base reaction. Here, \(\text{SiO}_2\), despite being a neutral oxide, behaves like an acidic oxide, reacting with the strong base \(\text{NaOH}\). The product, sodium silicate, is considered a type of salt in this context.
• Conversely, \(\text{SiO}_2\) reacting with \(\text{HF}\) involves an indirect acid-base concept. It is more of a neutralization reaction that forms a hexafluorosilicic acid. \(\text{HF}\) donates hydrogen ions leading to the formation of \(\text{H}_2\text{SiF}_6\) showing an interesting twist to typical acid behaviors, given \(\text{HF}\)'s ability to both dissolve and react with \(\text{SiO}_2\).

Understanding these reactions enhances comprehension of inorganic compounds' behavior when they encounter other reagents, especially how acidic and basic properties interplay to yield new products.

Balancing Equations

Balancing chemical equations is an essential skill in chemistry which ensures that the number of atoms for each element is conserved during reactions. It respects the Law of Conservation of Mass, which posits that mass cannot be created or destroyed in an isolated system.

For example, when balancing the first equation involving \(\text{SiO}_2\) and \(\text{NaOH}\), one needs to ensure that every atom present in the reactants is accounted for in the products:

• The entire equation \(\text{SiO}_2 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SiO}_3 + \text{H}_2\text{O}\) shows silicon and oxygen are balanced by forming sodium silicate plus water.
• For the second reaction \(\text{SiO}_2 + 6\text{HF} \rightarrow \text{H}_2\text{SiF}_6 + 2\text{H}_2\text{O}\), balancing the atoms involves ensuring silicon, hydrogen, and fluorine atoms fit appropriately, thereby forming hexafluorosilicic acid.

Approaching these reactions involves counting and adjusting the coefficients before reactants and products until the equation balances, maintaining the equality of atoms on both sides.