valence of magnesium is 2
and valence of sulfate-ion is 2 too
answer: MgSO4•7H2O
Answer:
The activation energy for an endothermic reaction is quite large and usually takes extra energy from the environment, it is normally not a natural spontaneous process.
Explanation:
- Endothermic reactions require absorbing energy of the surrounding mainly in the form of heat.
- Chemical energy needs energy input to break the bonds.
- Examples of endothermic reactions: Photosynthesis
, melting of ice
, and evaporating liquid water.
soluble substances dissolves in solvents
Answer:
Pf= 190 mmHg
Explanation:
(Pi×Vi)/Ti = (Pf×Vf)/<em>T2</em>
Initial Pressure Pi = 756mmHg,
Initial Volume Vi = 2L,
Initial Temperature Ti = 0°C=273K
Final Pressure Pf = ?,
Final Volume Vf = 2L+ Vi = 4L,
Final Temperature <em>T2</em>= 137K
Pf = (Pi × Vi × T2 )/(Vf × Ti)
Pf = (756 × 2 × 137)/(4 × 273)
Pf = 189.7 mmHg
Pf <em>approx.</em> 190mmHg
The mass, in grams, of NaCl needed to use to make the solution is 1.76grams.
<h3>HOW TO CALCULATE MASS?</h3>
The mass of a substance can be calculated by multiplying the number of moles by its molar mass.
However, the number of moles must first be calculated by using the following expression:
Molarity = no. of moles ÷ volume
no. of moles = 0.249 × 0.1208
no. of moles = 0.03moles
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
mass of NaCl = 0.03 × 58.5 = 1.76g
Therefore, the mass, in grams, of NaCl needed to use to make the solution is 1.76grams.
Learn more about mass at: brainly.com/question/19694949