CHEMISTRY MIDDLE SCHOOL

Are the following physical or chemical changes.1.Lighting a match
2.Cooking waffles
3.Baking a cake

Answers

Answer 1
Answer: They are all chemical changes. Think of a chemical change as you can never get something back to the way it was. (A lit match can't be turned back into a new one, waffles can't be turned back into waffle mix, and a cake can't be turned back into cake batter.)

Physical change would be something like slicing cheese or evaporating water. (The sliced cheese is still cheese, and the water turns into steam which can then be turned back into a liquid and it's still water - just in the air.)
Answer 2
Answer: chemical reactions because the chemical formula is changed in the reaction

Related Questions

6. What is SEAgel?a lightweight foam insulationa skin conditioner made from seaweeda semi-liquid semiconductor
Substances which will glow in the dark after being exposed to sunlight are:luminescentphosphorescentradioactivephotosensitive
Is it true that the formula for magnesium sulfate shows that there are four atoms of sulfur
A measure of the strength of acid rain can be given using _____. an acid a base a pH scale all of the above
What are ways you can collect and analyze data?

what is the molarity of a solution prepared by dissolving 1.25g of HCL gas into enough water to make 30cm cube of solution?

Answers

30 cm³ / 1000 = 0.03 L

Molar mass HCl = 36.46 g/mol

number of moles:

mass of solute / molar mass

1.25 / 36.46 = 0.03428 moles

M = n / V

M = 0.03428 / 0.03

M = 1.14267 mol/L⁻¹

hope this helps!

Boiling point and melting point of a gas?

Answers

it depends on the altitude of where u live

How does meiosis I differ from meiosis II

Answers

Meiosis 1 makes 2 Haploid cells from one Diploid cell. Meiosis 2 separates the sister chromatids in the haploid cell in order to make 4 daughter cells. 

how many protons electrons and neutrons does a atom with the atomic number 50 and mass number 125 contain?

Answers

Answer:

Protons: 50, Neutrons: 75, Electrons: 50

Explanation:

The atomic number, which in this case is 50, determines the number of protons and electrons an atom has. Take the atomic number and subtract the number of protons to get the number of neutrons.

C. If 62.9 g of lead (II) chloride is produced, how many grams of lead (II) nitrate werereacted?

Answers

Answer:

Mass = 76.176 g

Explanation:

Given data:

Mass of lead(II) chloride produced = 62.9 g

Mass of lead(II) nitrate used = ?

Solution:

Chemical equation:

Pb(NO₃)₂  +  2HCl     →     PbCl₂ + 2HNO₃

Number of moles of lead(II) chloride:

Number of moles = mass/molar mass

Number  of moles = 62.9 g/ 278.1 g/mol

Number of moles = 0.23 mol

Now we will compare the moles of lead(II) chloride with Pb(NO₃)₂ from balance chemical equation:

                            PbCl₂        :          Pb(NO₃)₂

                               1             :             1

                             0.23         :            0.23

Mass of Pb(NO₃)₂:

Mass = number of moles ×  molar mass

Mass = 0.23 mol × 331.2 g/mol

Mass = 76.176 g

How to separate a mixture of suger, water and sand

Answers

I believe the answer you’re looking for is Using distillation
Other Questions
Where do clouds form
Which of the following is a nonrenewable energy source?A) Nuclear Energy B) Wind Energy C) Hydroelectric Power D) Solar Energy
If you knew the number of valence electrons in a nonmetal atom how would you determine the valence of the element
Aqueous solutions of chromium(III) iodide and potassium hydroxide react to give a chromium(III) hydroxide precipitate and aqueous potassium iodide.Express your answer as a chemical equation. Identify all of the phases in your answer. Enter noreaction if there is no reaction.