how did barium hydroxide appear in the absence of CO2 and how it appear in the presence of CO2
Barium hydroxide is a chemical compound that can form under different conditions. To understand how it can appear in the absence or presence of carbon dioxide (CO2), we need to consider the reactions involved.
In the absence of CO2:
Barium hydroxide (Ba(OH)2) can be obtained by the reaction between barium oxide (BaO) and water (H2O). This process is an exothermic reaction, meaning it releases heat as a byproduct. The reaction can be represented as follows:
BaO + H2O → Ba(OH)2
In this case, the absence of CO2 indicates that there is no carbon dioxide gas present during the reaction.
In the presence of CO2:
When barium hydroxide reacts with carbon dioxide, it forms barium carbonate (BaCO3), water, and heat. This reaction is a precipitation reaction, resulting in the formation of a solid, barium carbonate. The reaction can be represented as follows:
Ba(OH)2 + CO2 → BaCO3 + H2O
The presence of CO2 triggers this reaction to produce barium carbonate.
To observe the appearance of barium hydroxide, you would need to perform specific experiments or reactions according to the conditions mentioned above. It is important to note that barium hydroxide itself is a white, odorless solid, which may not visibly change in appearance during these reactions. However, the appearance of barium hydroxide might be indicated by the formation of a precipitate (barium carbonate) or by other chemical indicators used in experiments to verify the presence of the compound.