1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Murljashka [212]
3 years ago
14

Which activity is an example of chemical change?

Chemistry
1 answer:
frutty [35]3 years ago
3 0
An old penny rusting, remember you can’t undo a chemical change
You might be interested in
Find the mole fraction of benzene and toluene in solution containing​
Mrac [35]

Answer:

The mole fraction of benzene and toluene in solution containing mole fraction of benzene and toluene in solution containing is 45.9%

Explanation:

don't worry

its is correct!

5 0
3 years ago
Calculate the amount of copper (in moles) in a 45.2 g pure copper sheet
tangare [24]

Answer:

0.712 mol

Explanation:

The easiest way to do this is to use a proportion.

1 mol of copper = 63.5 grams (check this using your periodic table).

x mol of copper = 45.2 grams

1/x = 63.5 / 45.2              Cross multiply

63.5 x = 1 * 45.2              Divide by 63.5

x = 45.2/63.5

x = 0.712 mol                   Answer to 3 sig digs

8 0
3 years ago
I have a brick, dimensions 4 cm tall, 9 cm wide, and 25 cm long, with a mass of 1250 g. What is the density?
Likurg_2 [28]

Answer:

1.389

Explanation:

P = m / V

m = 1250

V = 4x9x25 = 900

1250/900 = 1.388889

7 0
3 years ago
Hard water often contains dissolved Ca2+ and Mg2+ ions. One way to soften water is to add phosphates. The phosphate ion forms in
avanturin [10]
<span>5.5×10−2M in calcium chloride and 8.0×10−2M in magnesium nitrate.
What mass of sodium phosphate must be added to 1.5L of this solution to completely eliminate the hard water ion

1) Content of Ca (2+) ions

Calcium chloride = CaCl2

Ionization equation: CaCl2 ---> Ca (2+) + 2 Cl (-)

=> Molar ratios: 1 mol of CaCl2 : 1 mol Ca(2+) : 2 mol Cl(-)

Calculate the number of moles of CaCl2 in 1.5 liters of 5.5 * 10^-2 M solution

M = n / V => n = M*V = 5.5 * 10^ -2 M * 1.5 l = 0.0825 mol CaCl2

=> 0.0825 mol Ca(2+)

2) Number of phosphate ions needed to react with 0.0825 mol Ca(2+)

formula of phospahte ion: PO4 (3-)

molar ratio: 2PO4(3-) + 3Ca(2+) = Ca3 (PO4)2

Proportion: 2 mol PO4(3-) / 3 mol Ca(2+) = x / 0.0825 mol Ca(2+)

=> x = 0.0825 coml Ca(2+) * 2 mol PO4(3-) / 3 mol Ca(2+) = 0.055 mol PO4(3-)

3) Content of Mg(2+) ions

Ionization equation: Mg (NO3)2 ----> Mg(2+) + 2 NO3 (-)

Molar ratios: 1 mol Mg(NO3)2 : 1 mol Mg(2+) + 2 mol NO3(-)

number of moles of Mg(NO3)2 in 1.5 liter of 8.0 * 10^-2 M solution

n = M * V = 8.0 * 10^ -2 M * 1.5 liter = 0.12 moles Mg(NO3)2

ions of Mg(2+) = 0.12 mol Mg(NO3)2 * 1 mol Mg(2+) / mol Mg(NO3)2 = 0.12 mol Mg(2+)

4) Number of phosphate ions needed to react with 0.12 mol Mg(2+)

2PO4(3-) + 3Mg(2+) = Mg3(PO4)2

=> 2 mol PO4(3-) / 3 mol Mg(2+) = x / 0.12 mol Mg(2+)

=> x = 0.12 * 2/3 mol PO4(3-) = 0.16 mol PO4(3-)

5) Total number of moles of PO4(3-)

0.055 mol + 0.16 mol = 0.215 mol

6) Sodium phosphate

Sodium phosphate = Na3(PO4)

Na3PO4 ---> 3Na(+) + PO4(3-)

=> 1 mol Na3PO4 : 1 mol PO4(3-)

=> 0.215 mol PO4(3-) : 0.215 mol Na3PO4

mass in grams = number of moles * molar mass

molar mass of Na3 PO4 = 3*23 g/mol + 31 g/mol + 4*16 g/mol = 164 g/mol

=> mass in grams = 0.215 mol * 164 g/mol = 35.26 g

Answer: 35.26 g of sodium phosphate
</span>
5 0
3 years ago
What is the empirical mass of SO2?<br> Answer using four significant figures.
timofeeve [1]
The atomic mass is 64.07
3 0
3 years ago
Read 2 more answers
Other questions:
  • Which of the following are advantages of the SI system?
    6·2 answers
  • What is the density of an objects with a volume of 4.3 mL and a mass of 8.32g
    8·1 answer
  • 3. The nucleus:
    11·1 answer
  • If you use 19 mL of 0.100 M KMnO4, how many moles have you used? The answer has to be in four decimal places (do not forget the
    14·1 answer
  • Substances A, B, and C can all act as oxidizing agents. In solution, A is green, B is yellow, and C is red. In the reactions in
    5·1 answer
  • 1.<br> Which chemical equation represents a double replacement reaction?
    6·2 answers
  • help please thanks you
    8·1 answer
  • What is the process in which matter changes from the liquid to the solid state?
    8·2 answers
  • Describe the structure of a complex molecule such as plastic at the molecular level.​
    6·1 answer
  • Guys please helppp!!!!!
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!