It has more surface area.
greater surface are to volume ratio for a start which leads to faster dissolving particule theory: more collisions. there are more small pieces of sugar to collide in icing than granular
Icing sugar and caster sugar are not interchangeable. This is because icing sugar absorbs water whereas caster sugar does not. Switching icing sugar for caster in a baked good recipe will result in a good with a brick-like texture, whereas substituting caster sugar for icing will result in something liquidy and granular.
Yes it will the same as any other sugar, like white refined or icing sugar
It has more surface area.
In some cases yes, but not if you're making icing. Icing sugar is far finer grained, and as such caster sugar will not be an adequate replacement in this case. (Your icing will be granular and not set properly). You may be able to if it's a meringue recipe, but you'd be better off finding a recipe that does not use icing sugar to begin with.
No. Icing sugar is very finely ground, like a powder, so it dissolves in the butter and makes the frosting smooth. White sugar has little granules and if you use it in frosting your frosting will be grainy and crunchy.
YEP! It is not only the sweetening of sugar that is needed for baking, but the granular consistency. You CAN the make cookies, but they will no doubt not be as well formed as those made with granulated sugar.
When you mix icing sugar with water, the sugar dissolves in the water to create a sweet syrup that can be used for various purposes like glazing desserts or making royal icing for decorating cakes or cookies. The consistency of the mixture can be adjusted by adding more sugar or water as needed to achieve the desired thickness.
Not really; sugars other than powdered do not dissolve when used in a mixture that is not heated (such as icing). If the recipe already involves brown sugar, you can increase the quantity slightly without too many side-effects. However replacing powdered sugar (completely) with brown is likely to yield undesirable results; powdered sugar helps add 'smoothness' to icing, so without this you may end up with a very brown granular icing (that may not set adequately). If the recipe does not call for brown sugar at all, definitely do not add it.
Powdered sugar, icing sugar and confectioners sugar are all the same thing. It is usually known as icing sugar in England and powdered sugar in the USA. Confectioners sugar is used as an international name.These are the same thing. Powdered sugar, icing sugar, and confectioners sugar are just different names for sugar than has been ground to a fine powder so that it dissolves very easily.
Granular.
If you are making icing, yes. If you are making a meringue, no.