A process in which one or more substances (reactants) are transformed into entirely different substances (products) through the breaking and forming of chemical bonds, accompanied.
Old bonds break, new bonds form. You end up with different stuff than you started with.
Showing a random 20 of 50 problems.
Example 1
medium
Why does a color change during dye dissolving NOT prove a chemical reaction, but rusting's color change does?
Example 2
medium
In the reaction NaOH+HClโNaCl+H2โO, what is the product that is a salt?
Example 3
hard
A student observes that an iron nail in a copper sulfate solution becomes coated with copper and the blue color fades. Explain why this is a chemical reaction and write the products.
Example 4
challenge
A reaction in an open beaker appears to lose 2 g. Argue, using bonds and atoms, why no atoms were destroyed.
Example 5
medium
Identify the type of evidence in each: (a) blue solution turns green, (b) thermometer rises from 20ยฐC to 35ยฐC, (c) white solid sinks in clear liquid after mixing.
Example 6
easy
Name two pieces of evidence that a chemical reaction has occurred.
Example 7
easy
In the reaction Zn+2HClโZnCl2โ+H2โ, name the products.Name the products in this reaction.
Example 8
easy
Does a chemical reaction always require heating?
Example 9
challenge
Design a single experiment to prove that mixing solution A and B is a chemical reaction AND classify its energy change. Describe expected observations.
Example 10
easy
In a chemical reaction, what happens to chemical bonds?
Example 11
medium
Identify reactants and products in: 2H2โ+O2โโ2H2โO.