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4 years ago

16 Which change results in the formation of different substances?(1) burning of propane

Chemistry

2 answers:

Fofino [41]4 years ago

8 0

Answer:The correct answer is option (1).

Explanation:

Burning of propane in the presence of oxygen will form carbon-dioxide, water and heat.The chemical reaction can represented as in chemical equation:

$C_3H_8+5O_2\rightarrow 3CO_2+4H_2O+heat$

This is an example of chemical change where new product is formed.

Where as in melting of sold sodium chloride, deposition of carbon-dioxide gas and solidification of water ;phase of the substance is changing that is a physical change is taking place.

Hence, the correct option is (1).

Trava [24]4 years ago

6 0

1. The burning of propane creates different substances: propane and oxygen combine to create water and carbon dioxide:

C3H8 + 5 O2 becomes 3 CO2 + 4 H2O + heat

2. When NaCl melts, it is changing state, but it is still the same NaCl.

3. When gaseous CO2 deposits it is changing state, but it is still the same CO2.

4. When (presumably liquid) water solidifies, it is changing state, but it is still the same water.

So the answer is 1.

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Sergio [31]

Lipids cannot dissolve in water.

8 0

3 years ago

Read 2 more answers

Pharmacists sometimes measure medicines in the unit of "grains," where 1 gr = 65 mg. The label on a bottle of aspirin reads "Asp

viva [34]

Answer:

325mg of Aspririn

Explanation:

First you should note the information that the problem gives you:

- The bottle of Aspirin has 5gr (grains)

- 1gr(grain) = 65mg (miligrams)

Also, the problem is asking about how many aspirin are in 5 gr (grains), so you should use a conversion factor, as follows:

-First you should put the quantity you need to convert:

$5grAspirin$

-Then you write the denominator of the conversion factor that must have the same units that you want to convert, in this case gr:

$5grAspirin*\frac{}{1grAspirin}$

-Then you write the numerator with the units that you want to obtain and the numerical equivalence between the units, in this case:

$5grAspirin*\frac{65mgAspririn}{1grAspirin}$

-Finally you multiply numerators and divide by denominators:

$5grAspirin*\frac{65mgAspririn}{1grAspirin}=325mgAspririn$

8 0

4 years ago

A chemist fills a reaction vessel with 0.750 M lead (II) (Pb2+) aqueous solution, 0.232 M bromide (Br) aqueous solution, and 0.9

Ronch [10]

Answer:

The free energy = -20.46 KJ

Explanation:

given Data:

Pb²⁺ = 0.750 M

Br⁻ = 0.232 M

R = 8.314 Jk⁻¹mol⁻¹

T = 298K

The Gibb's free energy is calculated using the formula;

ΔG = ΔG° + RTlnQ -------------------------1

Where;

ΔG° = standard Gibb's freeenergy

R = Gas constant

Q = reaction quotient

T = temperature

The chemical reaction is given as;

Pb²⁺(aq) + 2Br⁻(aq) ⇄PbBr₂(s)

The ΔG°f are given as:

ΔG°f (PbBr₂) = -260.75 kj.mol⁻¹

ΔG°f (Pb²⁺) = -24.4 kj.mol⁻¹

ΔG°f (2Br⁻) = -103.97 kj.mol⁻¹

Calculating the standard gibb's free energy using the formula;

ΔG° = ξnpΔG°(product) - ξnrΔG°(reactant)

Substituting, we have;

ΔG° =[1mol*ΔG°f (PbBr₂)] - [1 mol *ΔG°f (Pb²⁺) +2mol *ΔG°f (2Br⁻)]

ΔG° =(1 *-260.75 kj.mol⁻¹) - (1* -24.4 kj.mol⁻¹) +(2*-103.97 kj.mol⁻¹)

= -260.75 + 232.34

= -28.41 kj

Calculating the reaction quotient Q using the formula;

Q = 1/[Pb²⁺ *(Br⁻)²]

= 1/(0.750 * 0.232²)

= 24.77

Substituting all the calculated values into equation 1, we have

ΔG = ΔG° + RTlnQ

ΔG = -28.41 + (8.414*10⁻³ * 298 * In 24.77)

= -28.41 +7.95

= -20. 46 kJ

Therefore, the free energy of reaction = -20.46 kJ

8 0

3 years ago

Help me please an thank you

miskamm [114]

Molecular formula

hope that helps^^

6 0

3 years ago

What is the ph of a 0.006 m koh solution? 1. 11.78 2. 7.00 3. 2.22 4. 8.88 5. 5.12?

Stels [109]

The concentration of OH⁻ is first converted to pOH bu using followinf formula,

pOH = -log [OH⁻]
Putting value,
pOH = -log (0.006)

pOH = 2.221
As we know,
pH + pOH = 14
Solving for pH,
pH = 14 - pOH
Putting value of pOH,
pH = 14 - 2.221

pH = 11.779
Result:
Option-1 is the correct answer.

4 0

3 years ago