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4 years ago

The mass spectrum represented above is most consistent with which of the following elements? Eu Gd Tb Dy

Chemistry

1 answer:

Kryger [21]4 years ago

3 0

Answer:

The mass spectroscopy is most consistent with the element Gd

Explanation:

Here we have the average atomic mass given by the weighted average found by multiplying the abundance in nature of the various isotopes by their observed atomic masses followed by the summation of the multiplication results as follows;

Based on approximate measurement of the chart, we have the values for the relative abundance given as follows;

Isotope, I Relative abundance, A I×A

154 1 154

155 6 930

156 8 1248

157 6.2 973.4

158 10 1580

160 8.5 1360

Sum 39.7 6245.5

Average atomic mass = 6245.5/39.7 = 157.314 atomic mass unit

Atomic mass of Eu = 151.964 u

Atomic mass of Gd = 157.25 u

Atomic mass of Tb = 158.92535 u

Atomic mass of Dy = 162.5 u

Therefore, the mass spectroscopy is most consistent with the element Gd.

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The amount of heat absorbed when 5.5g of aluminum is heated from 25.0c to 95.0c the specific heat of aluminum is 0.897J/(gc)

NemiM [27]

Answer:

Q=21.99 kJ

Explanation:

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3 years ago

In the citric acid cycle, ATP molecules are produced by _____. In the citric acid cycle, ATP molecules are produced by _____. su

monitta

Answer:

substrate-level phosphorylation

Explanation:

Substrate-level phosphorylation is the metabolic reaction which results in formation of energy currency molecules, ATP or GTP by direct transfer of a phosphoryl group to the ADP or GDP from the another phosphorylated compound.

In citric acid cycle, Succinyl-CoA in the presence of succinyl-CoA synthase is converted to succinate. Condensation reaction (Substrate-level phosphorylation) of GDP and Pi takes place which results in the formation of GTP.

3 0

3 years ago

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]

Answer: The mass of methane burned is 12.4 grams.

Explanation:

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.

For process 1:

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

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:

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

For process 2:

$q_2=m\times L_v$

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:

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

For process 3:

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

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

Nascar fans love race day when they get a chance to cheer on there favorite racer if a driver was able to travel 600 miles in 3

hjlf

Answer:

200 mph

Explanation:

600/3=200

5 0

3 years ago

14. Explain, in terms of ions, why a 10.0-milliliter sample of 0.10 M NH4Cl(aq) is a poorer conductor of

Licemer1 [7]

Ionic compounds conduct electricity when dissolved in water, because the free-floating ions can carry charge. The more ions you have, the more readily the solution will carry that charge. 10.0 mL of 0.10 M NH4Cl has only 0.001 mol of NH4+ and 0.001 mol of Cl-, whereas 10.0 mL of 0.30 NH4Cl has 0.003 mol of NH4+ and 0.003 mol of Cl-. The 0.10 M sample is a poorer conducted of electricity because it has less ions in solution.

3 0

3 years ago