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babunello [35]
3 years ago
11

Which event always involves a chemical change A boiling B melting C conducting D burning

Chemistry
1 answer:
Andrew [12]3 years ago
4 0
The answer is Burning
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Dissolving 5.28 g of an impure sample of calcium carbonate in hydrochloric acid produced 1.14 l of carbon dioxide at 20.0 °c an
kvv77 [185]

Answer:

Percentage by mass of calcium carbonate in the sample is 93.58%.

Explanation:

Assumptions:

  • calcium carbonate was dissolved completely and the amount of carbon dioxide released was proportional to the amount of calcium carbonate.
  • the sample did not contain any other compound that released or reacted with carbon dioxide.

PV = nRT

n = \frac{PV}{RT}

P = 791 mmHg = \frac{791 mmHg}{760 mmHg} x 1 atm = 1.040789 atm.

R = 8.314 \frac{J}{K*mol} = 0.082 \frac{L*atm}{K*mol}

T = 20^{0}C + 273^{0} C = 293 K

n = \frac{1.040789 atm * 1.14 L}{0.082 \frac{L * atm}{K * mol} * 293 K }

n = 0.0493839 mol.

given the equation of the reaction:

CaCO_{3}  + 2HCL =  CaCl_{2}  + CO_{2} + H_{2}O

from assumption:

amount carbon dioxide = amount of calcium carbonate

n(CaCO_{3} ) = n(CO_{2} )

reacting mass ( m )  = Molar Mass ( M ) * Amount ( n )

m(CaCO_{3} )   =   n(CaCO_{3} )  *   M(CaCO_{3} )

m = 0.04938397 mol * 100 \frac{g}{mol} =  4.93839 g

percentage by mass of   CaCO_{3} = \frac{mass of pure  }{mass of impure}*100  = \frac{4.93839g}{5.28g}*100  = 93.5802%.

8 0
3 years ago
14 Which property is a measure of the average kinetic energy of the particles in a sample or matter?
FrozenT [24]
(4) temperature is the correct answer.

Average kinetic energy is calculated by 3/2*R*T, in which R is a constant and is equal to 8.3145 J/ mol*K, and T is temperature measured in Kelvins.

Hope this helps~
3 0
3 years ago
Into how many peaks will each proton shown in red be split
Tamiku [17]
The proton has two adjacent protons, so it splits into three peaks, a triplet. The proton has three adjacent protons, so it splits into four peaks, a quartet.
8 0
3 years ago
When water is solid, do molecules move?
BabaBlast [244]

Answer:

Ice is water in its solid form. Ice keeps its shape, even if it's removed from the container. The molecules in ice are locked into place and cannot move or slide past one another, but they do vibrate a little bit.

Explanation:

As the temperature drops or decreases, the water molecules gradually slow down. Eventually they stop moving and simply vibrate back and forth. At this point ice is formed, the solid phase of water. If the temperature is allowed to increase, the molecules will once again begin to vibrate faster and faster.

8 0
3 years ago
Read 2 more answers
A sample of aluminum is placed in a 25-ml graduated cylinder containing 10.0 ml of water. the level of the water rises to 18.0 m
OLga [1]
To determine the mass of the sample, first find the volume difference after and before the aluminum was placed, the volume change is equal to the volume of the submerged object, in this case aluminum.

Then knowing volume of aluminum and the density of it, we can solve for the mass.

D = m/v

Dv = m

2.7 g/ml • 8 ml = 21.6 grams.
5 0
3 years ago
Read 2 more answers
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