Are the following examples physical changes or chemical changes.
Mixing yeast and sugar
Dissolving sugar in water
Slicing bread
Baking bread
Melting cheese
I think mixing yeast and water, melting cheese, and baking bread is chemical.
I think dissolving sugar in water and slicing bread is physical
Yes?
what do you think?
To determine whether each example is a physical change or a chemical change, we need to understand the difference between the two.
A physical change refers to a change in the state or appearance of a substance without altering its chemical composition. In other words, the substance remains the same at a molecular level, even though its physical properties may change.
A chemical change, on the other hand, involves a transformation at the molecular level. This means that the original substances are changed into new substances with different chemical properties.
Now let's analyze each example:
1. Mixing yeast and sugar: This is a physical change. When you mix yeast and sugar, the individual substances are simply combined, but there is no chemical reaction taking place. The yeast and sugar particles remain the same.
2. Dissolving sugar in water: This is also a physical change. When you dissolve sugar in water, the sugar particles disperse into the water, creating a homogeneous mixture. No new chemical substances are formed; it is only the physical state of the sugar that changes.
3. Slicing bread: This is a physical change. Slicing bread may change its shape and size, but it does not alter its chemical composition. The bread remains the same at a molecular level.
4. Baking bread: This is a chemical change. When you bake bread, several chemical reactions occur. The yeast in the dough produces carbon dioxide, which causes the bread to rise. The heat also causes the proteins and starches in the dough to undergo chemical changes, resulting in the formation of a new substance with different properties: bread.
5. Melting cheese: This is a physical change. Melting cheese involves heating it, causing the cheese to change from a solid to a liquid state. However, the chemical composition of the cheese remains the same.
In conclusion, the mixing of yeast and sugar, dissolving sugar in water, and slicing bread are physical changes, while baking bread is a chemical change, and melting cheese is a physical change.