Concentration of a solution can be expressed in terms of molarity and molality
Molarity is the number of moles of solute in a liter of a solution.
Molarity (M) = Moles of solute/Volume(litres) of solution
Molality is the number of moles of solute in one kg of the solution
Molality (m) = Moles of solute/Mass (kg) of solution
Therefore if the volume or the mass of the solution is changed this would affect the concentration.
In addition, volume is a quantity which depends on temperature. However, mass is independent of temperature. Therefore any changes in temperature, can also bring about a change in the molarity of the solution.
Answer : The final temperature of the metal block is, 
Explanation :
As we know that,
![m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)]](https://tex.z-dn.net/?f=m_1%5Ctimes%20c_1%5Ctimes%20%28T_%7Bfinal%7D-T_1%29%3D-%5Bm_2%5Ctimes%20c_2%5Ctimes%20%28T_%7Bfinal%7D-T_2%29%5D)
.................(1)
where,
q = heat absorbed or released
= mass of aluminum = 55 g
= mass of water = 0.48 g
= final temperature = ?
= temperature of aluminum =
= temperature of water =
= specific heat of aluminum = 
= specific heat of water= 
Now put all the given values in equation (1), we get
![55g\times 0.900J/g^oC\times (T_{final}-25)^oC=-[0.48g\times 4.184J/g^oC\times (T_{final}-25)^oC]](https://tex.z-dn.net/?f=55g%5Ctimes%200.900J%2Fg%5EoC%5Ctimes%20%28T_%7Bfinal%7D-25%29%5EoC%3D-%5B0.48g%5Ctimes%204.184J%2Fg%5EoC%5Ctimes%20%28T_%7Bfinal%7D-25%29%5EoC%5D)
Thus, the final temperature of the metal block is,
Answer:
Isotopes of an element share the same number of protons but have different numbers of neutrons. Let's use carbon as an example. There are three isotopes of carbon found in nature – carbon-12, carbon-13, and carbon-14. All three have six protons, but their neutron numbers - 6, 7, and 8, respectively - all differ.
Explanation:
Answer:
308 moles of sodium
Explanation:
The balanced equation for the chemical reaction between sodium metal (Na) and water (H₂O) is the following:
2 Na(s) + 2 H₂O → 2 NaOH(aq) + H₂(g)
From the equation, we can see that 2 moles of Na react with 2 moles of H₂O to give 2 moles of NaOH and 1 mol of H₂ (hydrogen gas). So the stoichiometric mole ratio between Na and H₂ is: 2 mol Na/1 mol H₂. Thus, we multiply the mole ratio by the moles of H₂ to be produced to obtain the moles of Na required:
moles of Na required = 2 mol Na/1 mol H₂ x 154 moles H₂ = 308 moles Na
Therefore, 308 moles of sodium are needed to produce 154 moles of hydrogen gas.
Answer: Option (c) is the correct answer.
Explanation:
Plants used to prepare food in the presence of sunlight. Therefore, plants uses solar energy to make food.
Due to solar energy various chemical reactions take place in the food.
Thus, we can conclude that chemical energy is stored in our food and this chemical energy start out as light energy from the sun.
