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2 years ago

What are some examples of physical changes?

2 answers:

5 0

Answer: Melting of ice to water is a physical change. Evaporation, Freezing are also physical change. Cutting of wood, breaking of glass are also examples. Any change in size and phase but does not change its chemical composition is an example of a physical change.

Explanation:

Ludmilka [50]2 years ago

3 0

Some examples of physical changes are:

Breaking a glass

Chopping wood

Tearing paper

Mixing sand and water

Melting an ice cube

These all are physical changes because the composition of the matter does not change.

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3 years ago

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What are the four types of biological molecules and their main function in the human body?

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Answer:

There are four major classes of biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids)

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3 years ago

Ethanol (c2h5oh) melts at -114Â°c. the enthalpy of fusion is 5.02 kj/mol. the specific heats of solid and liquid ethanol are 0.9

Nimfa-mama [501]

Answer: 4.18925 kJ heat is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.

Explanation:

Temperature of Solid $C_2H_5OH=-135^oC=138 K(0^oC=273K)$

Melting temperature of Solid $C_2H_5OH=114^oC=159 K$

Temperature of liquid $C_2H_5OH=-50^oC=223K$

Specific heats of solid ethanol = 0.97 J/gK

Specific heats of liquid ethanol = 2.3 J/gK

Heat required to melt the the 25 g solid $C_2H_5OH$ at 159 K

$\Delta T_1$ = 159 K - 138 K = 21 K

$Q_1=mc\Delta T= 25\times 0.97J/gK\times 21 K=509.25 J$

Heat required to melt and raise the temperature of $C_2H_5OH$ upto 223 K

$\Delta T_2$ = 223 K - 159 K = 64 K

$Q_2=mc\Delta T= 25\times 2.3J/gK\times 64 K=3680 J$

Total heat to convert solid ethanol to liquid ethanol at given temperature :

$Q_1+Q_2=509.25 J+3680 J=4189.25 J=4.18925 kJ$ (1kJ=1000J)

Hence, 4.18925 kJ of heat will be required to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.

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2 years ago

Please help ASAP! I’m lost right now.

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Mark as brainliest if this helped! :)

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3 years ago

Please help I’ll mark brainleist

kozerog [31]

Answer: with what?

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2 years ago

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