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3 years ago

How much heat is given off when 18.5g of water at 35.0 degrees Celsius freezes to ice at -5.00 degrees Celsius

Chemistry

1 answer:

saveliy_v [14]3 years ago

5 0

9086.3J

Explanation:

Given parameters:

Mass of water = 18.5g

Initial temperature of water = 35°C

Finial temperature = -5°C

Unknown:

Amount of heat given off = ?

Solution:

In converting the water to ice, the water goes through these processes:

35°C to freezing point at 0°C = mcΔT

0°C of water to 0°C of ice = mL

0°C of ice to -5°C = mcΔT

The heat given off;

H = mc₁ΔT + mL + mc₂ΔT

m is the mass of water

c₁ is the specific heat capacity of water = 4.2J/g °C

c₂ is the specific heat capacity of ice = 2.03J/g °C

L is the latent heat of fusion = 334J/g

ΔT = T₂ - T₁ = temperature change

H = 18.5 x 4.2 + (0-(-35)) + (18.5 x 334) + (18.5 x 2.03 x (-5 - (0))

H = 2719.5J + ‬6179J + 187.8J = 9086.3J

learn more:

Specific heat brainly.com/question/7210400

#learnwithBrainly

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How much mass of sodium chloride ( ) should be dissolved in water to make 1.5 L of 0.75 M aqueous solution? The molar mass of is

iogann1982 [59]

Answer:

Mass = 65.8 g

Explanation:

Given data:

Mass of sodium chloride = ?

Volume of solution = 1.5 L

Molarity of solution = 0.75 M

Solution:

Number of moles of sodium chloride:

Molarity = number of moles / volume in L

By putting values,

0.75 M = number of moles = 1.5 L

Number of moles = 0.75 M × 1.5 L

Number of moles = 1.125 mol

Mass of sodium chloride:

Mass = number of moles × molar mass

Mass = 1.125 mol × 58.5 g/mol

Mass = 65.8 g

4 0

2 years ago

zn (s) 2 hcl (aq) -----> zncl2 (aq) h2(g) if 520 ml of h2 is collected over water at 28oc and the atmospheric pressure is 1.0

nadya68 [22]

The Zn that is 1.33 g is used at the start of the reaction where f is 520 ml and h2 collected over water is 28oc and the atmospheric pressure is 1.0 atm.

Given If 520 ml of H2 is gathered over Wate at 28 diploma Celsius and the atmospheric strain is 1 ATM if vapour strain of wate at 28 diploma celsius is 28.three mmhg then the quantity of zn in grams taken at begin of the response is.

We recognise that

h * 2 = PT - P * h * 20 = 1atm - 0.037atm

= 0.963 atm

1 * h * 2 = Ph * 2V / R * T

= 0.963 atm x 0.520 L / 0.0821 L atm/

molK * 301

= 0.02 mol h2

= 0.02molZn

So 0.02 mol Zn x 65.39 g/mol

= 1.33 g Zn

Read more about zinc;

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3 0

1 year ago

A laser pulse with wavelength 545 nm contains 4.85 mJ of energy. How many photons are in the laser pulse?

dusya [7]

Given:

Wavelength (λ) of the laser pulse = 545 nm = 5.45 * 10⁻⁹ m

Total energy of pulse = 4.85 mJ

To determine:

The number of photons in the laser of a given energy

Explanation:

Energy per photon (E) = hc/λ

where h = planck's constant = 6.626 *10⁻³⁴ Js

C = speed of light = 3*10⁸ m/s

λ = wavelength

E = 6.626 *10⁻³⁴ Js* 3*10⁸ms-1 /5.45 * 10⁻⁹ m = 3.65 * 10⁻¹⁹ J

Now,

# photons = total energy/Energy per photon

= 4.85 * 10⁻³ J* 1 photon / 3.65 * 10⁻¹⁹ J = 1.32 * 10¹⁶ photons

Ans: the laser pulse contains 1.32 * 10¹⁶ photons

3 0

3 years ago

WILL GIVE BRAINLIEST IF YOU EXPLAIN (this is 7th grade Science / Chemistry btw):

alekssr [168]

Answer:

2 chlorine atoms.

Explanation:

H₂ + Cl₂ → 2HCl

The Law of Conservation of Mass states that matter can neither be created nor destroyed in a chemical reaction.

If 2 molecules of Hydrogen and 2 molecules of Chlorine is present in the reactants, the same no. of atoms should also be present in the product.

∴ the no. of chlorine atoms in the product is 2.

8 0

3 years ago

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AfilCa [17]

Cause and Effect relationship questions can be answered through science. Science can't answer definite explanations of a question but can show the relationships that they have concluded through research. As an example I did an experiment when I was a kid on mold growing on applesauce if Cinnamon slowed growth or not. I could conclude that there did seem to be a relationship with cinnamon and applesauce that cinnamon slowed growth. I can't say it definitely proved it it just showed the relationship.

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3 years ago