All categories

3 years ago

Which of the following is an example of a chemical change?

Chemistry

1 answer:

alexdok [17]3 years ago

3 0

Answer:

Dissolving sugar in water, burning paper, and melting gold are all chemical changes

Explanation:

The action cannot be reversed, or undone. Therefore it is a chemical change.

Boiling water is a physical change.

You might be interested in

A. Based on the activation energies and frequency factors, rank the following reactions from fastest to slowest reaction rate, a

deff fn [24]

Answer:

A) $E_{a} = 350KJ/mol$ , $E_{a} = 50KJ/mol$ , $E_{a} = 50KJ/mol$

A = 1.5× $10^{-7}s^{-1}$ , A = 1.9× $10^{-7} s^{-1}$ , A=1.5× $10^{-7} s^{-1}$

B) 4.469

Explanation:

From Arrhenius equation

$K=Ae^{\frac{E_{a} }{RT} }$

where; K = Rate of constant

A = Pre exponetial factor

$E_{a}$ = Activation Energy

R = Universal constant

T = Temperature in Kelvin

Given parameters:

$E_{a} =165KJ/mol$

$T_{1}=505K$

$T_{2}=525K$

$R=8.314JK^{-1}mol^{-1}$

taking logarithm on both sides of the equation we have;

$InK=InA-\frac{E_{a} }{RT}$

since we have the rate of two different temperature the equation can be derived as:

$In(\frac{K_{2} }{K_{1} } )=\frac{E_{a} }{R}(\frac{1}{T_{1} } -\frac{1}{T_{2} } )$

$In(\frac{K_{2} }{K_{1} } )=\frac{165000J/mol}{8.314JK^{-1}mol^{-1} }.(\frac{1}{505} -\frac{1}{525} )$

$In(\frac{K_{2} }{K_{1} } )$ = 19846.04×7.544× $10^{-5}$ = 1.497

$\frac{K_{2} }{K_{1} }$ = $e^{1.497}$ = 4.469

6 0

3 years ago

Which process releases energy by breaking down glucose and other food molecules in the presence of oxygen?

FinnZ [79.3K]

Cellular respiration

is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

5 0

4 years ago

Read 2 more answers

Chuck wants to know how many electrons in an atom are not paired up. Which model would be best for Chuck to

loris [4]

Answer:

D. an orbital notation of the atom

Explanation:

Orbital notiation uses lines and arrows to show shells, subshells, and orbitals for electrons in an atom. Since it shows arrows being paired up in this diagram it would be the best model for Chuck to use.

4 0

3 years ago

2HgO(s)---->2Hg(I)+O2(g) which type of reaction occurs

kaheart [24]

Decomposition,because 1 breaks down into 2

8 0

3 years ago

Read 2 more answers

What is the osmotic pressure, in torr, of a 3.00% solution of NaCl in water when the temperature of the solution is 45 ºC? Enter

Anit [1.1K]

213034 torr is the osmotic pressure.

Explanation:

osmotic pressure is calculated by the formula:

osmotic pressure= iCrT

where i= no. of solute

c= concentration in mol/litre

R= Universal Gas constant

T = temp

It is given that solution is 3% which is 3gms in 100 ml.

let us calculate the concentration in moles/litre

3gm/100ml*1000ml/1L*1mol NaCl/55.84g NaCl

= 5.372 gm/litre

Putting the values in the formula, Temp in Kelvin 318.5K

osmotic pressure= 2*5.372*0.083 * 318.5 Gas constant 0.083

= 284.023 bar or 213018 torr. c= 5.372 moles/L

i=2 for NaCl

4 0

3 years ago