B. SiCl4
C. NaCl
D. Na2O
The compound of an element in period 3 that reacts with water to form a solution with a pH greater than 7 is:
D. Na₂O (sodium oxide)
In period 3 of the periodic table, the elements are sodium (Na) and silicon (Si), among others. Let's analyze the options:
A. SiO₂ (silicon dioxide) does not react with water to form a solution with a pH greater than 7. It is an acidic oxide and can react with water to form a weakly acidic solution.
B. SiCl₄ (silicon tetrachloride) is not a compound that reacts with water to form a solution with a pH greater than 7. It hydrolyzes with water to produce hydrochloric acid, which leads to a decrease in pH (more acidic).
C. NaCl (sodium chloride) does not react with water to form a solution with a pH greater than 7. It is a neutral compound and does not affect the pH of water.
D. Na₂O (sodium oxide) reacts vigorously with water to form sodium hydroxide (NaOH), a strong base. Sodium hydroxide is highly soluble in water and completely dissociates into hydroxide ions (OH⁻) and sodium ions (Na⁺). The presence of hydroxide ions in the solution makes it basic, resulting in a pH greater than 7.
Therefore, the correct answer is D. Na₂O (sodium oxide).
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Answer:
The main basis for the classification system is the way rocks were formed. With these criteria there are three different types of rocks:
(AHC H20(I) = -285.8 kJ/mol)
A -120.9 kJ
B-241.8 kJ
C-571.6 kJ
D-285.8 kJ
Answer:
The heat of reaction when hydrogen and oxygen combine to form water is :
C. 571.6 kJ
Explanation:
Enthalpy Change = The enthalpy change for the formation of 1 mole of the substance from their standard state is called the enthalpy of formation.
This is intensive quantity as it is fixed for 1 mole .
Intensive properties = Those properties which are independent on the amount of the substance are intensive properties.
The value of these quantities does not get halve if you divide the substance into two equal parts. example , density, refractive index.
However , the enthalpy of reaction is extensive. Because on increasing the amount the value of the enthalpy also get doubles
Hence for this reaction :
Its value is -285.8 kJ for 1 mole
And here two moles are present . so the value of molar enthalpy is:
-285.8 x 2 = -571.6 kJ