Double arrow means reversible reaction while single arrow represents complete reaction.For strong acid such as HCl,they undergo ionization to form H+ and Cl-.For weak acid such as H2CO3,it undergoes reversible reaction.
H2CO3->H+ + HCO3-
HCO3- <->H+ + CO3 2-
The double arrow in a dissociation equation for a weak acid represents that the reaction can occur in both the forward and reverse directions. Weak acids only partially dissociate in water, so the equilibrium can shift in either direction depending on the conditions.
Strong acids, such as HCl, dissociate almost completely in water to produce H+ ions and the corresponding anions. Since the dissociation is essentially complete, only one arrow is used to indicate the direction of the reaction towards product formation. This implies that the reaction is highly favored in the forward direction.
The arrow that is used to indicate a reverse or backward reaction in a chemical equation is called a double-headed arrow.
Symbols for the different states of matter are just the first letter of the state in lower case (with the exception of aqueous which has the first two letters in lower case). Only gas and solid have an extra symbol which is the up or down arrow (which I cannot demonstrate here... will not let me insert symbols):Solid = (s) or Liquid = (l)Gas = (g) or ­Aqueous = (aq)
The common abbreviations for state are (s) for solid, (g) for gas, (l) for liquid, and (aq) for aqueous solution. Of these, (aq) and (s) are likely to be the important ones for precipitation. Sometimes a down arrow is used to emphasize that a precipitate is formed.
The double arrow in a dissociation equation for a weak acid represents that the reaction can occur in both the forward and reverse directions. Weak acids only partially dissociate in water, so the equilibrium can shift in either direction depending on the conditions.
Strong acids, such as HCl, dissociate almost completely in water to produce H+ ions and the corresponding anions. Since the dissociation is essentially complete, only one arrow is used to indicate the direction of the reaction towards product formation. This implies that the reaction is highly favored in the forward direction.
arrow in heel
This depends on how the double arrow is drawn. Most of the lines if not all will be parallel.
See related links for a picture of a cursor double-headed arrow.
Double up arrow or double down arrow + Grind
On the drawing toolbar, go to autoshape->connectors, and the double arrow is in there.
An arrow is a graphical symbol used to point or indicate direction.
Arrow
This means that the reaction in question takes place in an aqueous solution. Even when water does not take part in a reaction, many things - most things, actually - will be more chemically active if dissolved in water, than in solid form.
They are arrow points and double arrow points
The arrow that is used to indicate a reverse or backward reaction in a chemical equation is called a double-headed arrow.