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strojnjashka [21]
3 years ago
8

The first coin has a density of approximately 19. What kind of metal is it​

Chemistry
1 answer:
umka21 [38]3 years ago
4 0

Answer: Its a A Cent.

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There are four hundred participants in the local Thanksgiving 5K race. If 51% of the participants are female, what is the ratio
Paha777 [63]

Answer:

51:49 is the ratio of female participants to male participants.

Explanation:

Percentage of females in the race = 51 %

Percentage of males in the race = 100% - 51 % = 49%

Total participants in race = 400

Number of women participants = 51% of 400=\frac{51}{100}\times 400=204

Number of men participants  = 49% of 400=\frac{49}{100}\times 400=196

Ratio of female participants to male participants :

\frac{204}{196}=\frac{51}{49}=51:49

5 0
4 years ago
Predict whether the changes in enthalpy, entropy, and free energy will be positive or negative for the freezing of water, and ex
Dafna11 [192]

Answer:

Explanation:

The total energy or intrinsic energy of a system is called the enthalpy. In thermochemistry, we have two types of enthalpy changes which are:

  • Exothermic changes
  • Endothermic changes

For the freezing of water, the enthalpy change is an exothermic one. Exothermic changes are designated as negative. In this chemical change, heat is liberated to the surroundings and this leaves the environment at a much higher temperature. In freezing, the enviroment gains more heat as the material begins to cool to lower temperature.

Entropy is the degree of randomness or disorderliness of a system. When a phase change occurs from liquid to solid, freezing takes place. Such a change increases the orderliness of a system and entropy diminishes. Here, entropy is negative.

The free energy is a measure of the energy a system that does useful work. Free energy depends on enthalpy, entropy and temperature of a system. For phase changes such as freezing of water, the value of free energy change is 0.

For this process, an increases in temperature makes it non-spontaneous. Increasing temperature would alter the course of the reaction and makes it exothermic. For entropy, increasing temperature would increase entropy and therefore, the reaction would not be feasible.

Temperature would mostly affect the free energy. An increase in temperature would increase the value of entropy change and the reaction would not be spontaneous. With falling temperature value, the reaction becomes more spontaneous and favored.

8 0
3 years ago
The equilibrium constant Kc for the equation2H2(g) + CO(g) ⇌ CH3OH(g)is 35 at a certain temperature. If there are 3.21 ×10−2 mol
12345 [234]

Answer: the concentration of [CO]= 0.0532M

Explanation:

From The equation of reaction

2H2(g) + CO(g) ⇌ CH3OH(g)

Applying Kc= [CH3OH]/[H2]^2[[CO]

[CH3OH]= 0.00487

[CO]= x-0.00487

[H2]=(0.032-0.00487)^2=0.0271

Substitute into formula

Kc=[CH3OH]/[H2]^2[[CO]

35= 0.00487/(0.0271)^2(x-0.00487)

Simplify

x-0.00487=0.189

x= 0.00487+0.189=0.193moles

[CO]= n/C= 0.193/3.63= 0.0532M

8 0
3 years ago
The Al2O3 crystal structure (corundum) consists of an HCP arrangement of O2- ions; the Al3+ ions occupy octahedral positions. Wh
vesna_86 [32]

Answer:

The fraction of the available octahedral positions are filled with Al^{3+} ions is \frac{2}{3}

Explanation:

If there are n numbers of spheres in HCP in packing:

Number of octahedral void = n

Number of tetrahedral void = 2n

Total number of voids = n + 2n = 3n

The Al_2O_3 crystal structure consists of an HCP arrangement of O^{2-}ions.

Number of spheres in HCP = 6

Number of O^{2-} = 6

Number of octahedral voids = 6

Number of tetrahedral void = 12

Number of aluminum ions when there are 6 O^{2-} ion =\frac{2}{3}\times 6= 4

Number of voids in which Al^3+ ions are present = 4

The fraction of the available octahedral positions are filled with Al^{3+} ions = \frac{4}{6}=\frac{2}{3}

5 0
4 years ago
If 0.138g of cyclohexene (c6h10) was obtained from 0.240g of cyclohexanol (c6h120), what is the percentage yield of cyclohexene?
tino4ka555 [31]
<span>Given in the question- 1 mole of cyclohexanol = > 1 mole of cyclohexene Molar mass 100.16 g/mol moles of cyclohexanol = .240 / 100.16= 0.002396 moles Molar mass 82.143 g/mol moles of cyclohexene formed @100 % yield = 0.002396 Molar mass 82.143 g/mol mass of cyclohexene @ 100 % = .002396 x 82.143 = 0.197g bur we have .138g so % yield = .138 / .197 = 70.0 % Ans- 70 percentage yield of cyclohexene.</span>
4 0
4 years ago
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