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2 years ago

How much energy is required to heat 2kg of ice from -5°c to 0°c

Chemistry

1 answer:

balu736 [363]2 years ago

4 0

Explanation:

total heat = Heat required to convert 2 kg of ice to 2 kg of water at 0 °C + Heat required to convert 2 kg of water at 0 °C to 2 kg of water at 20 °C.

Heat=mhfg+mCpΔT

Here, m ( mass of ice) = 2 kg

hfg (latent heat of fusion of ice) = 334 KJ

Cp of water (specific heat) = 4.187 KJ/Kg-K

ΔT(Temperature difference) = 20 °C

Therefore, Heat required = 2 x 334 + 2 x 4.187 x (20 - 0 )

Heat reqd= 835.48 KJ

Therefore, to melt 2 kg of ice 835.48 KJ of heat is required.

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A solution contains 3.1 mM Zn(NO3)2 and 4.2 mM Ca(NO3)2. The p-function for Zn2+ is _____, and the p-function for NO3- is _____.

seropon [69]

Answer: The p-function of $Zn^{2+}$ and $NO_3^{-}$ ions are 2.51 and 2.14 respectively.

Explanation:

p-function is defined as the negative logarithm of any concentration.

We are given:

Millimolar concentration of zinc nitrate = 3.1 mM

Millimolar concentration of calcium nitrate = 4.2 mM

Converting this into molar concentration, we use the conversion factor:

1 M = 1000 mM

Concentration of zinc nitrate = 0.0031 M = 0.0031 mol/L

1 mole of zinc nitrate produces 1 mole of zinc ions and 2 moles of nitrate ions

Concentration of zinc ions = 0.0031 M

Concentration of nitrate ions in zinc nitrate, $M_1=(2\times 0.0031)=0.0062M$

Concentration of calcium nitrate = 0.0042 M = 0.0042 mol/L

1 mole of calcium nitrate produces 1 mole of calcium ions and 2 moles of nitrate ions

Concentration of calcium ions = 0.0042 M

Concentration of nitrate ions in calcium nitrate, $M_2=(2\times 0.0042)=0.0084M$

To calculate the concentration of nitrate ions in the solution, we use the equation:

$M=\frac{M_1V_1+M_2V_2}{V_1+V_2}$

Putting values in above equation, we get:

$M=\frac{(0.0062\times 1)+(0.0084\times 1)}{1+1}\\\\M=0.0073M$

Calculating the p-function of zinc ions and nitrate ions in the solution:

For zinc ions:

$\text{p-function of }Zn^{2+}\text{ ions}=-\log[Zn^{2+}]$

$\text{p-function of }Zn^{2+}\text{ ions}=-\log(0.0031)\\\\\text{p-function of }Zn^{2+}\text{ ions}=2.51$

For nitrate ions:

$\text{p-function of }NO_3^{-}\text{ ions}=-\log[NO_3^{-}]$

$\text{p-function of }NO_3^{-}\text{ ions}=-\log(0.0073)\\\\\text{p-function of }NO_3^{-}\text{ ions}=2.14$

Hence, the p-function of $Zn^{2+}$ and $NO_3^{-}$ ions are 2.51 and 2.14 respectively.

5 0

3 years ago

The mass of a nucleus is 0.042 amu less than the sum of the masses of 3 protons and 4 neutrons. The binding energy per nucleon i

Leni [432]

The answer is 10 mev. hope this helps

4 0

3 years ago

Read 2 more answers

Determine the energy in joules of a photon whose frequency is 3.55 x10^17 hz

zaharov [31]

The equation for energy of a photon is E=hv where v equals frequency and h equals the Planck constant (6.626X10^-34). So since you've been given frequency you can just plug in frequency to find the total energy in joules.

E=(3.55X10^17)(6.626X10^-34)
E=2.35223X10^-16

Not sure how many significant figures you needed. Hope this helped.

4 0

3 years ago

Mature elephants consume an average of 600 pounds of food per day. If an elephant

MAXImum [283]

Answer:

$\large \boxed{\text{4 600 000 kg or 4600 Mg}}$

Explanation:

1. Calculate the adult life

If the elephant is an adult from its 10th birthday until the day before its 56th birthday, its

Adult life = 55 - 10 + 1 = 46 yr

2. Convert years to days

$\text{Adult life} = \text{46 yr} \times \dfrac{\text{365.25 da}}{\text{1 yr}} = \text{16 800 da}$

3. Convert days to pounds of feed

$\text{Feed} = \text{16 800 da} \times \dfrac{\text{600 lb}}{\text{1 da}} = 1.01 \times 10^{7} \text{ lb}$

4. Convert pounds to kilograms and megagrams

$\text{Feed} =1.01 \times 10^{7} \text{ lb} \times \dfrac{\text{1 kg}}{\text{2.20 lb}} =\textbf{4 600 000 kg} = \textbf{4600 Mg}\\\\\text{The elephant will eat $\large \boxed{\textbf{4 600 000 kg or 4600 Mg}}$ of food.}$

Note: The answer can have only two significant figures because that is all you gave for age of the elephant.

5 0

3 years ago

Key words how atoms work?

pantera1 [17]

Most atoms have three different subatomic particles inside them: protons, neutrons, and electrons. The protons and neutrons are packed together into the center of the atom(which is called the nucleus) and the electrons, which are very much smaller, whizz around the outside. Most of an atom is empty space.

I hope this helps you! :D

3 0

2 years ago