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4 years ago

6

as electrons are passed through the system of electron carriers associated with photosystem ii, they lose energy. what happens t

o this energy?

1 answer:

katrin2010 [14]4 years ago

7 0

They break up and become only positive energy

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Calculate the mass of methane that must be burned to provide enough heat to convert 242.0 g of water at 26.0°C into steam at 101

Anarel [89]

<u>Answer:</u> The mass of methane burned is 12.4 grams.

<u>Explanation:</u>

The chemical equation for the combustion of methane follows:

$CH_4(g)+2O_2(g)\rightarrow CO_2(g)+2H_2O(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(CO_2(g))})+(2\times \Delta H^o_f_{(H_2O(g))})]-[(1\times \Delta H^o_f_{(CH_4(g))})+(2\times \Delta H^o_f_{(O_2(g))})]$

We are given:

$\Delta H^o_f_{(H_2O(g))}=-241.82kJ/mol\\\Delta H^o_f_{(CO_2(g))}=-393.51kJ/mol\\\Delta H^o_f_{(CH_4(g))}=-74.81kJ/mol\\\Delta H^o_f_{O_2}=0kJ/mol$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(1\times (-393.51))+(2\times (-241.82))]-[(1\times (-74.81))+(2\times (0))]\\\\\Delta H^o_{rxn}=-802.34kJ$

The heat calculated above is the heat released for 1 mole of methane.

The process involved in this problem are:

$(1):H_2O(l)(26^oC)\rightarrow H_2O(l)(100^oC)\\\\(2):H_2O(l)(100^oC)\rightarrow H_2O(g)(100^oC)\\\\(3):H_2O(g)(100^oC)\rightarrow H_2O(g)(101^oC)$

Now, we calculate the amount of heat released or absorbed in all the processes.

<u>For process 1:</u>

$q_1=mC_p,l\times (T_2-T_1)$

where,

$q_1$ = amount of heat absorbed = ?

m = mass of water = 242.0 g

$C_{p,l}$ = specific heat of water = 4.18 J/g°C

$T_2$ = final temperature = $100^oC$

$T_1$ = initial temperature = $26^oC$

Putting all the values in above equation, we get:

$q_1=242.0g\times 4.18J/g^oC\times (100-(26))^oC=74855.44J$

<u>For process 2:</u>

$q_2=m\times L_v$

where,

$q_2$ = amount of heat absorbed = ?

m = mass of water or steam = 242 g

$L_v$ = latent heat of vaporization = 2257 J/g

Putting all the values in above equation, we get:

$q_2=242g\times 2257J/g=546194J$

<u>For process 3:</u>

$q_3=mC_p,g\times (T_2-T_1)$

where,

$q_3$ = amount of heat absorbed = ?

m = mass of steam = 242.0 g

$C_{p,g}$ = specific heat of steam = 2.08 J/g°C

$T_2$ = final temperature = $101^oC$

$T_1$ = initial temperature = $100^oC$

Putting all the values in above equation, we get:

$q_3=242.0g\times 2.08J/g^oC\times (101-(100))^oC=503.36J$

Total heat required = $q_1+q_2+q_3=(74855.44+546194+503.36)=621552.8J=621.552kJ$

To calculate the number of moles of methane, we apply unitary method:

When 802.34 kJ of heat is needed, the amount of methane combusted is 1 mole

So, when 621.552 kJ of heat is needed, the amount of methane combusted will be = $\frac{1}{802.34}\times 621.552=0.775mol$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Molar mass of methane = 16 g/mol

Moles of methane = 0.775 moles

Putting values in above equation, we get:

$0.775mol=\frac{\text{Mass of methane}}{16g/mol}\\\\\text{Mass of methane}=(0.775mol\times 16g/mol)=12.4g$

Hence, the mass of methane burned is 12.4 grams.

8 0

3 years ago

A 32.78 g sample of a substance is initially at 22.7 °c. after absorbing 2017 j of heat, the temperature of the substance is 173

larisa86 [58]

Heat= mass * change in temperature* specific heat
specific heat=409 J/kg K

3 0

4 years ago

When a reaction forms between atoms with ground state electron configuration 1s22s2 and 1s22s22p5 the predominant type of bond f

Arisa [49]

C. Ionic is the answer

6 0

3 years ago

astraxan [27]

Answer

mass of 1 mole = 18g

mass of 1 mL = 1g

the unit used is gram

Explanation:

There are two ways to find mass of water:

1st way:

If we find Mass of water for one mole of water:

For this purpose we use mole formula as below

no. of moles = mass in grams / molar mass

if we find mass for one mole of water:

then

no. of moles of water = 1 mol

molar mass of water = H₂O = (1x2 +1x16) = 18 g/mol

mass of water = ?

Put the value in the mole formula

no. of moles = mass in grams / molar mass . . . . . . . . . . . . (1)

by rearranging the formula (1)

mass in grams = no. of moles x molar mass

mass in grams = 1 mole x 18 g/mol

mass in grams = 18 g

So for one mole of water the mass of water is 18 g and the unit for it is gram.

2nd way:

We can find mass of water by another way too

if we find the mass 1 mL of water

then the formula will be used is

D = m/v

where D is density

m is the mass

and v is the volume

So

density of water for 1 mL (D) = 1 g/ml

volume of water = 1 mL

mass of water = ?

By Rearranging density formula for mass

m = D/v ......................... (2)

put the values in equation 2

m= 1gmL⁻¹ / 1 mL

m= 1g

So the mass of 1mL is 1g

7 0

4 years ago

Nah I'm gonna fail this quiz help please

Eva8 [605]

Answer:

It has 2 eyes

Explanation:

Quantitive observation means that it is facts based of numbers, therefore you can count how many eyes it has, but not that it has red eyes

4 0

3 years ago