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kipiarov [429]
3 years ago
15

Which process is endothermic?a)b)c)d)The evaporation of water from the skin.The burning of candle wax.The oxidation of iron in a

chemical hand warmer.The combustion of natural gas in a stove
Chemistry
1 answer:
BlackZzzverrR [31]3 years ago
6 0

Answer:

The answer is option a. The evaporation of water from the skin

Explanation:

An endothermic reaction is any synthetic reaction that retains heat from its environment. The ingested energy gives the enactment energy to the reaction to happen.

No new bonds formed, no bonds broken in this example. water molecules go from liquid to vapour (gas ), intermolecular bond exist between polar (-OH) molecules and energy is required to break these bonds during the change from liquid to gas. So, it is endothermic .

Remaining three above examples are exothermic. combustion of gas releases energy(exothermic). burninig of the candle exothermic because the energy released from the oxygen into carbon dioxide and water.oxidation of iron also exothermic

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corrected question:

Determining Density and Using Density to Determine Volume or Mass

(a) Calculate the density of mercury if 1.00 × 10 g occupies a volume of 7.36 cm³

(b) Calculate the volume of 65.0 g of liquid methanol (wood alcohol) if its density is 0.791 g/mL.

(c) What is the mass in grams of a cube of gold (density = 19.32 g/cm) if the length of the cube is 2.00 cm?

(d) Calculate the density of a 374.5-g sample of copper if it has a volume of 41.8 cm³ A student needs 15.0 g of ethanol for an experiment. If the density of ethanol is 0.789 g/mL, how many milliliters of ethanol are needed? What is the mass, in grams, of 25.0 mL of mercury (density = 13.6 g/mL)?

Answer:

density = \frac{mass}{volume}

ρ=m/v ,m=ρv,    v=m/ρ

(a)m=1*10g  , v=7.36cm³

    ρ=10/7.36 =1.36g/cm³

(b) m=65g, ρ=0.791 g/mL.

   v= 65/0.791 =82.17g/mL

(c) ρ=19.32g/cm³, l=2cm, v=l³=8cm³

    m=19..32*8=154.56g/cm³

(d) mass of copper=374.5g , v=41.8cm³

   ρ=374.5/41.8 =8.96g/cm³

 mass of ethanol=15g,  density of ethanol=0.789g/mL

v=15/0.789 =19.01mL

volume of mecury=25mL, density of mercury=13.6g/mL

m=25*13.6=340g

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<h3>What is bonding in molecules?</h3>

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