Answer: 2.26x 10²⁴ atoms C
Explanation: To get the number of atoms,
First we convert mass of C to moles
45g C x 1mole C / 12 g C
= 3.75 moles C
Cancel g of C
Next convert moles of C to atoms using Avogadro's Number.
3.75 moles C x 6.022x10²³ atoms C / 1 mole C
Cancel out the units of moles C.
= 2.26x 10²⁴ atoms of C
Answer: A. Exothermic reaction
Explanation: Enthalpy change for a reaction is sum of enthalpy of formation of products minus sum of enthalpy of formation of reactants.
When the energy level of reactants is above as compared to the products, the reaction is exothermic and when its opposite then reaction is endothermic.
From given information, the potential energy diagram starts at 380 kJ means the energy level of reactants is 380 kJ. It ends at 100 kJ means the energy of products is 100 kJ.
Enthalpy of reaction = 100 kJ - 380 kJ
Enthalpy of reaction = -280 kJ
Negative sign of enthalpy change indicates an Exothermic reaction.
Answer:
Explanation:
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In this case, since it is observed that hot cadmium is placed in cold water, we can infer that the heat released due to the cooling of cadmium is gained by the water and therefore we can write:
Thus, we insert mass, specific heat and temperatures to obtain:
In such a way, since the specific heat of cadmium and water are respectively 0.232 and 4.184 J/(g °C), we can solve for the equilibrium temperature (the final one) as shown below:
Now, we plug in to obtain:
NOTE: since the density of water is 1g/cc, we infer that 25.00 cc equals 25.00 g.
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