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vovangra [49]
3 years ago
15

Which of the following is NOT a sign (indicator) that a chemical reaction has occurred?

Chemistry
1 answer:
hoa [83]3 years ago
3 0

Answer:

C

Explanation:

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"What is the change of entropy for 3.0 kg of water when the 3.0 kg of water is changed to ice at 0"
Artyom0805 [142]

Q: What is the change of entropy for 3.0 kg of water when the 3.0 kg of water is changed to ice at 0 °C? (Lf = 3.34 x 105 J/kg)

Answer:

-3670.33 J/K

Explanation:

Entropy: This can be defined as the degree of randomness or disorderliness of a substance. The S.I unit of Entropy is J/K.

Mathematically,  change of Entropy can be expressed as,

ΔS = ΔH/T ....................................... Equation 1

Where ΔS = Change of entropy, ΔH = heat change, T = temperature.

ΔH = -(Lf×m).................................... Equation 2

Note: ΔH is negative because heat is lost.

Where Lf = latent heat of ice = 3.34×10⁵ J/kg, m = 3.0 kg, m = mass of water = 3.0 kg

Substitute into equation

ΔH = -(3.34×10⁵×3.0)

ΔH = - 1002000 J.

But T = 0 °C = (0+273) K = 273 K.

Substitute into equation 1

ΔS = -1002000/273

ΔS = -3670.33 J/K

Note: The negative value of ΔS shows that the entropy of water decreases when it is changed to ice at 0 °C

4 0
3 years ago
It took batman 5 minutes to catch robin in the bat-mobile. If he traveled 45 km before catching him, how fast was he going?
Nataly_w [17]

Answer:

he going zoom zoom

Explanation:

7 0
3 years ago
Which sentence best describes the relationship between chlorophyll and the chloroplast?
Viktor [21]

Answer:

chlorophyll is a chemical found in a chloroplast

3 0
4 years ago
An experimental spacecraft consumes a special fuel at a rate of 372 L/min. The density of the fuel is 0.730 g/mL and the standar
Karolina [17]

Explanation:

First, we will calculate fuel consumption is as follows.

         372 L/min \times 1000 ml/L \times 0.730 g/ml \times \frac{1}{60} min/s

           = 4526 g/s

Now, we will calculate the power as follows.

        Power = Fuel consumption rate × -enthalpy of combustion

                    = 4526 g/s \times -26.5 kJ/g

                    = 1.19 \times 10^{5} kW

Thus, we can conclude that maximum power (in units of kilowatts) that can be produced by this spacecraft is 1.19 \times 10^{5} kW.

5 0
3 years ago
When the concentration of hydrogen lons equals the concentration of hydroxide ions, is called the ?
Ira Lisetskai [31]

Answer:

neutral pH or neutral solution

Explanation:

when hydrogen ion concentration and hydroxide ion concentration the pH is neutral i.e. ph=pOH=7

3 0
3 years ago
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