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vovikov84 [41]
1 year ago
7

Commercially available hot packs are simple in design: a pouch with water on one side, isolated by a barrier from a specific sal

t on the other side. When the barrier is broken, the salt and water mix and the solution becomes hot. Select the statement that is true about the reaction occurring in hot packs.A. The hot pack absorbs heat from the environment.
B. The reaction between the salt and water is exothermic.
C. The reaction between the salt and water is endothermic.
D. The reaction between the salt and water is neither endothermic nor exothermic.
Chemistry
1 answer:
liq [111]1 year ago
3 0

Answer:

b :)

Explanation:

an exothermic reaction is when heat/light is produced. heart is produced from this reaction so it is exothermic

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Calculate the Lattice Energy of KCl(s) given the following data using the Born-Haber cycle: ΔHsublimation K = 79.2 kJ/mol IE1 K
DanielleElmas [232]

Answer:

Explanation:

  The following equation relates to Born-Haber cycle

\triangle H_f = S + \frac{1}{2} B + IE_M - EA_X+ U_L

Where

\triangle H_f is enthalpy of formation

S is enthalpy of sublimation

B is bond enthalpy

IE_M is ionisation enthalpy of metal

EA_X is electron affinity of non metal atom

U_L is lattice energy

Substituting the given values we have

-435.7 = 79.2 + 1/2 x 242.8 + 418.7 - 348 +U_L

U_L = - 707 KJ / mol

3 0
1 year ago
Water flows over Niagara Falss at the average rate of 2,400,000 kg/s, and the average height of the falls is about 50 m. Knowing
liberstina [14]

Answer:

1. 176 × 10^12 W ; 78400000000

Explanation:

Given the following :

Fall rate = 2,400,000kg/s

Average height of fall = 50m

Gravitational Potential of falling water = mgh = mass × acceleration due to gravity × height =

How many 15 W LED light bulbs could it power?

Recall : power = workdone / time

Workdone = gravitational potential energy

Mass of water = density * volume

Density of water = 1 * 10^3kg/m^3

Rate of fow = volume / time = 2400000

Hence,

Power = 1000 * 2,400,000 * 9.8 * 50

Power = 1176000000000

Power = 1. 176 × 10^12 W

How many 15 W LED light bulbs could it power?

1176000000000 / 15 = 78400000000

= 78400000000 15 W bulbs

4 0
2 years ago
The density of o2 gas at 16 degrees Celsius and 1.27atm is?
velikii [3]

Answer:

The density of O₂ gas is 1.71 \frac{g}{L}

Explanation:

Density is a quantity that allows you to measure the amount of mass in a given volume of a substance. So density is defined as the quotient between the mass of a body and the volume it occupies:

density=\frac{mass}{volume}

An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of the gases:

P * V = n * R * T

So, you can get:

\frac{n}{V} =\frac{P}{R*T}

The relationship between number of moles and mass is:

n=\frac{mass}{molar mass}

Replacing:

\frac{\frac{mass}{molar mass} }{V} =\frac{P}{R*T}

\frac{mass}{V*Molar mass} =\frac{P}{R*T}

So:

\frac{mass}{V} =\frac{P*molar mass}{R*T}

Knowing that 1 mol of O has 16 g, the molar mass of O₂ gas is 32 \frac{g}{mol}.

Then:

\frac{mass}{V} =\frac{P*molar mass of O_{2} }{R*T}

In this case you know:

  • P=1.27 atm
  • molar mass of O₂= 32 \frac{g}{mol}.
  • R= 0.0821 \frac{atm*L}{mol*K}
  • T= 16 °C=  289 °K (0°C= 273°K)

Replacing:

density=\frac{mass}{V} =\frac{1.27atm*32\frac{g}{mol}  }{0.0821\frac{atm*L}{mol*K} *289 K}

Solving:

density= 1.71 \frac{g}{L}

<u><em>The density of O₂ gas is 1.71 </em></u>\frac{g}{L}<u><em></em></u>

3 0
1 year ago
During an experiment, the percent yield of calcium chloride from a reaction was 85.22%. Theoretically, the expected amount shoul
devlian [24]

The formula to find yield is

(Actual Yield)/(Theorectical Yield) x100

Just do the math.

85.22% x 113 = 96.2986

Convert it to 3 significant figures

Ans: 96.3g

7 0
2 years ago
Read 2 more answers
The mass of radium-226 in a sample is found to have decreased from 45.00g to 5.625g in a period of 4800 years.From this informat
yan [13]

Answer:

Half life = 1600 years

Explanation:

Given data:

Total mass of sample = 45.00 g

Mass remain = 5.625 g

Time period = 4800 years

Half life of radium-226 = ?

Solution:

First of all we will calculate the number of half lives passes,

At time zero 45.00 g

At first half life = 45.00 g/ 2= 22.5 g

At 2nd half life = 22.5 g/ 2 = 11.25 g

At 3rd half life = 11.25 g/ 2= 5.625 g

Half life:

Half life = Time elapsed / number of half lives

Half life = 4800 years / 3

Half life = 1600 years

4 0
1 year ago
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