There are a few telltale signs that can help indicate that a chemical reaction has taken place; these include the creation of one or more new substances and a noticeable energy change from the reaction site. However, telling whether a chemical reaction has actually taken place is not always very easy to observe.Continue Reading
These changes can be noted in two different ways, through appearance changes and energy changes.
It is important to note that these signs are merely indicators, not proof, that a reaction has taken place and that the only true sign that a chemical reaction has occurred is the creation of one or more substances as a result of the chemical interaction.Learn more about Chemistry
The effect of a catalyst on a chemical reaction is to increase the rate of that reaction by reducing its activation energy. This activation energy is the energy required to move chemical reactants into a transition state, which is intermediate between reactant and product.Full Answer >
When sugar is burned, chemical changes take place, depending on if the sugar is burned in a complete or an incomplete combustion reaction. During a complete combustion reaction, sugar is transformed into CO2 and H20. In an incomplete combustion reaction that uses lower heat, ring polymerization and charring may occur.Full Answer >
Lemonade is a mixture because sugar, water and lemons are combined together without a chemical reaction taking place. The bonds of the substances can't combine with one another, instead the three items are mixed up.Full Answer >
Physical changes do not produce new substances, but chemical changes do produce new substances. A physical change is concerned with states of matter. Melting, vaporization, freezing, sublimation and condensation are physical changes. Melting an ice cube is a physical change because the substance remains as water. Most physical changes are reversible. Crushing a can, boiling water, breaking glass, chopping wood, mixing sand and water, and shredding paper are physical changes.Full Answer >