Answer: A characteristic test for hydrogen (H2) gas can be performed by bringing a burning candle near the source of hydrogen. On doing so, hydrogen gas burns with a squeaky pop sound. Hydrogen gas is recognized by the 'pop' when it burns. The 'pop' is the sound of a small explosion.
Explanation:
what does the ph scale actually measure?
pH scale measures whether the aqueous solution is acidic or basic. It is a measure of concentration of hydronium ion.
The term acidity and alkalinity are measured with a logarithmic scale called pH scale. pH is a measure of how acidic or basic the water is. It is a scale used to specify the acidity or basicity of an aqueous solution. Acidic solutions are measured to have lower pH values than basic solutions or alkaline solutions. The objects that are not very acidic are called basic objects. The pH scale has values ranging from zero that is the most acidic to 14 that is the most basic. Pure water has a pH value of 7. This value of 7 is considered as neutral that is neither acidic or basic.
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Calculate the standard enthalpy change for the reaction at 25 ∘ C. Standard enthalpy of formation values can be found in this list of thermodynamic properties. Mg(OH)2(s)+2HCl(g)⟶MgCl2(s)+2H2O(g)
ΔH∘rxn =
The standard enthalpy change for the reaction at the 25 °C is the -16.3 kJ.
The chemical reaction is as follows :
Mg(OH)₂(s) + 2HCl(g -----> MgCl₂(s) + 2H₂O(g)
The ΔHf Mg(OH)₂ = - 924.5 kJ/mol
The ΔHf HCl = - 92.30 kJ/mol
The ΔHf MgCl₂ = - 641.8 kJ/mol
The ΔHf H₂O = -241.8 kJ/mol
The standard enthalpy change of the rection is as :
ΔH∘rxn = ∑ ΔHf product - ∑ ΔHf reactant
= ( -641.8 + (2× -241.8 ) - ( - 924.5 + ( 2 × - 92.30 ))
ΔH∘rxn = - 16.3 kJ
The enthalpy change for the reaction is -16.3 kJ.
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