valerie placed 1.0g of salt into one beaker, 1.0g of soil into a second beaker, and 2.0g of sugar in a third beaker. She then added 200mL of water to each beaker and stirred the contents for 3 mintues. How many compounds and how many mixtures did Valerie make? Identify each. Explain whether a chemical or physical change took place in each beaker.
Tell me what your problem is in understanding this. Do you know the definitions of mixture, compounds, and chemical/physical changes?
i'm suppposed to be in 7th grade but they skipped me up to 8th
Good for you but that doesn't answer by questions. What do you not understand? Do you know the definitions? Perhaps I could help with the definitions?
i don't know the definitons because they are confusing.
http://www.chem.purdue.edu/gchelp/atoms/elements.html
To determine the number of compounds and mixtures created and whether a chemical or physical change took place, we'll need to understand the definitions of compounds, mixtures, chemical changes, and physical changes.
A compound is a substance that is made up of two or more different elements chemically combined in a fixed ratio. A mixture, on the other hand, is a combination of two or more substances that are physically blended together but can be separated by physical means.
A chemical change is a process that results in the formation of new substances with different properties, while a physical change is a process that does not involve the formation of new substances and only affects the physical properties of a substance.
Now let's analyze the given scenario:
1. In the first beaker, Valerie placed 1.0g of salt and added 200mL of water. Salt (NaCl) is a compound composed of sodium (Na) and chlorine (Cl) ions. When salt dissolves in water, the compound splits into individual sodium and chloride ions. This dissolution is a physical change, as it does not involve a chemical reaction. Therefore, in the first beaker, what Valerie created is a mixture of water and dissolved salt.
2. In the second beaker, Valerie placed 1.0g of soil and added 200mL of water. Soil is a mixture composed of various substances, such as minerals, organic matter, water, and air. When water is added to the soil, it dissociates some of the components of the soil, but no new substances are formed. This is also a physical change, and Valerie created a mixture of water and wet soil.
3. In the third beaker, Valerie placed 2.0g of sugar and added 200mL of water. Sugar (sucrose, C12H22O11) is a compound made up of carbon, hydrogen, and oxygen atoms. When sugar dissolves in water, it breaks down into individual sugar molecules. Similar to the first beaker, this dissolution is a physical change, so Valerie created a mixture of water and dissolved sugar in the third beaker.
To summarize:
- Valerie created three mixtures: a mixture of water and dissolved salt, a mixture of water and wet soil, and a mixture of water and dissolved sugar.
- No chemical changes took place in any of the three beakers since no new substances were formed. Only physical changes occurred with the dissolution of the compounds into their individual components.