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Salsk061 [2.6K]
2 years ago
8

The human body is about 9.5% carbon atoms, with a small fraction of that carbon being radioactive carbon-14. Carbon dating is a

method of determining the age of things made of once living materials. What information would be needed to find the age of a human fossil or the Dead Sea Scrolls?
Chemistry
1 answer:
maw [93]2 years ago
8 0

Answer:The age can be determined by utilizing carbon-14, a radioactive isotope of carbon.

Explanation:

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A compound has been shown to contain 14.5 percent hydrogen and 85.5 percent carbon by mass.
Sedaia [141]

Answer:

  • <em>Option d. Its empirical formula is CH</em><em>₂</em><em>.</em>

Explanation:

The percent composition of the compound allow you to calculate the empirical formula of the compound but is not enough to calculate either the molar mass or the molecular formula. So, since now you can discard options b. and c.

Telling that it is a hydrocarbon (option e.) is true but very vague compared with finding the empirical formula. So, you can also discard the option e.

The fact that the product has a triple bond cannot be concluded from the percent composition, you should find the molecular formula to assert whether it contains or not a triple bond. So, you could discard option a., which lets you only with choice d.

Let us find the empirical formula to be certain that it is CH₂.

1.  <u>First, assume a basis of 100 g of compound</u>:

  • H: 14.5% × 100 g = 14.0 g
  • C: 85.5% × 100 g = 85.5 g

2. <u>Divide each element by its atomic mass to find number of moles</u>:

  • H: 14.0 g / 1.008 g/mol = 14.38 mol
  • C: 85.5 g / 12.011 g/mol = 7.12 mol

3. <u>Divide both amounts by the smallest number, to find the mole ratio</u>:

  • H: 14.38 mol / 7.12 mol ≈ 2
  • C: 7.12 mol / 7.12 mol = 1.

Hence, the ratio is 2:1 and the empirical formula is CH₂.

7 0
2 years ago
A balloon is floating around outside your window. The temperature outside is 21 ∘C , and the air pressure is 0.700 atm . Your ne
Andreyy89

Answer:

V=162L

Explanation:

Hello,

In this case, we can compute the required volume by using the ideal gas equation as shown below:

PV=nRT

Thus, solving for the volume and considering absolute temperature (in Kelvins), we obtain:

V=\frac{nRT}{P}= \frac{4.70mol*0.082\frac{atm*L}{mol*K}*(21+273)K}{0.700atm} \\\\V=162L

Best regards.

4 0
3 years ago
The symbol of the period five element that is a member of the pnicitides family
Zepler [3.9K]

The symbol of the period five element that is a member of the pnicitides family are antimony.

Explanation:

Pnictogen family

  • In periodic table, column 15 elements are Pnitogen family.
  • The pnictogen elements are Nitrogen-N, arsenic-As, phosphorus-P, bismuth-Bi, antimony-Sb, ununpentium-Uup.    
  • There are five valence electrons each member of pnictogen family. In group 15 double bonds and triple bonds are formed due to these valence electrons.  
  • Pnictides, binary compounds of  group 15.

Antimony  

  • Antimony is the element found in period 5 and block p.
  • A chemical element, Antimony (Sb) from Latin word stibium and 51 is its atomic number. It is in solid state.
  • In ancient times, antimony compounds are used as cosmetic and medicine.
  • Appeared as semi metal.  
  • Electronic configurations of Sb is [Kr] 4d105s25p3.

7 0
2 years ago
PLZ HELP For the reaction: 2NO2(g) → N2O4(l),
Furkat [3]

Answer: \Delta H_{rxn}=-20kJ/mol-(+66kJ/mol)

Explanation:

Heat of reaction or enthalpy change is the energy released or absorbed during the course of the reaction.

It is calculated by subtracting the enthalpy of reactants from the enthalpy of products.

\Delta H=H_{products}-H_{reactants}

\Delta H = enthalpy change = ?

H_{products} = enthalpy of products

H_{reactants} = enthalpy of reactants

For the given reaction :

2NO_2(g)\rightarrow N_2O_4(l)

\Delta H=H_{N_2O_4}-2\times H_{NO_2}

\Delta H=-20kJ/mol-(+66kJ/mol)

6 0
3 years ago
A 1.00 g sample of octane (C8H18) is burned in a bomb calorimeter with a heat capacity of 837J∘C that holds 1200. g of water at
lubasha [3.4K]

Answer:

The heat of combustion for 1.00 mol of octane is  -5485.7 kJ/mol

Explanation:

<u>Step 1:</u> Data given

Mass of octane = 1.00 grams

Heat capacity of calorimeter = 837 J/°C

Mass of water = 1200 grams

Temperature of water = 25.0°C

Final temperature : 33.2 °C

<u> Step 2:</u> Calculate heat absorbed by the calorimeter

q = c*ΔT

⇒ with c = the heat capacity of the calorimeter = 837 J/°C

⇒ with ΔT = The change of temperature = T2 - T1 = 33.2 - 25.0 : 8.2 °C

q = 837 * 8.2 = 6863.4 J

<u>Step 3:</u> Calculate heat absorbed by the water

q = m*c*ΔT

⇒ m = the mass of the water = 1200 grams

⇒ c = the specific heat of water = 4.184 J/g°C

⇒ ΔT = The change in temperature = T2 - T1 = 33.2 - 25  = 8.2 °C

q = 1200 * 4.184 * 8.2 =  41170.56 J

<u>Step 4</u>: Calculate the total heat

qcalorimeter + qwater = 6863.4 + 41170. 56 = 48033.96 J  = 48 kJ

Since this is an exothermic reaction, there is heat released. q is positive but ΔH is negative.

<u>Step 5</u>: Calculate moles of octane

Moles octane = 1.00 gram / 114.23 g/mol

Moles octane = 0.00875 moles

<u>Step 6:</u> Calculate heat combustion for 1.00 mol of octane

ΔH = -48 kJ / 0.00875 moles

ΔH = -5485.7 kJ/mol

The heat of combustion for 1.00 mol of octane is  -5485.7 kJ/mol

8 0
2 years ago
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