Answer:
1.3 M.
Explanation:
- We need to calculate the mass of the solution:
mass of the solution = mass of MgCl₂ + mass of water
mass of MgCl₂ = 20.1 g.
mass of water = d.V = (157.0 mL)(1.0 g/cm³) = 157.0 g.
∴ mass of the solution = mass of MgCl₂ + mass of water = 20.1 g + 157.0 g = 177.1 g.
- Now, we can get the volume of the solution:
V of the solution = (mass of the solution)/(density of the solution) = (177.1 g)/(1.089 g/cm³) = 162.62 mL = 0.163 L.
Molarity is the no. of moles of solute dissolved in a 1.0 L of the solution.
M = (no. of moles of MgCl₂) / (Volume of the solution (L)).
<em>∴ M = (mass/molar mass)of MgCl₂ / (Volume of the solution (L)) =</em> (20.1 g/95.211 g/mol) / (0.163 L) = <em>1.29 M ≅ 1.3 M.</em>
Answer: ΔH for the reaction is -277.4 kJ
Explanation:
The balanced chemical reaction is,

The expression for enthalpy change is,
![\Delta H=\sum [n\times \Delta H(products)]-\sum [n\times \Delta H(reactant)]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5Csum%20%5Bn%5Ctimes%20%5CDelta%20H%28products%29%5D-%5Csum%20%5Bn%5Ctimes%20%5CDelta%20H%28reactant%29%5D)
![\Delta H=[(n_{CCl_4}\times \Delta H_{CCl_4})+(n_{HCl}\times B.E_{HCl}) ]-[(n_{CH_4}\times \Delta H_{CH_4})+n_{Cl_2}\times \Delta H_{Cl_2}]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B%28n_%7BCCl_4%7D%5Ctimes%20%5CDelta%20H_%7BCCl_4%7D%29%2B%28n_%7BHCl%7D%5Ctimes%20B.E_%7BHCl%7D%29%20%5D-%5B%28n_%7BCH_4%7D%5Ctimes%20%5CDelta%20H_%7BCH_4%7D%29%2Bn_%7BCl_2%7D%5Ctimes%20%5CDelta%20H_%7BCl_2%7D%5D)
where,
n = number of moles
Now put all the given values in this expression, we get
![\Delta H=[(1\times -139)+(1\times -92.31) ]-[(1\times -74.87)+(1\times 121.0]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B%281%5Ctimes%20-139%29%2B%281%5Ctimes%20-92.31%29%20%5D-%5B%281%5Ctimes%20-74.87%29%2B%281%5Ctimes%20121.0%5D)

Therefore, the enthalpy change for this reaction is, -277.4 kJ
Answer: 
Explanation:
Given : Sample size : n= 30 , it means it is a large sample (n≥ 30), so we use z-test .
Significance level : 
Critical value: 
Sample mean : 
Standard deviation : 
The formula to find the confidence interval is given by :-

i.e. 
i.e. 

Hence, the 95% confidence interval for the mean mpg in the entire population of that car model = 
Answer:
the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.