0.70 moles of an unknown solid is placed into water to make 150.0 mL of solution. The solution's temperature decreases by 8.4°C. Calculate ∆H for the dissolution of the unknown solid. (The specific heat of the solution is 4.18 J/g･°C and the density of the solution is 1.02 g/mL).

Explanation:

1. Mass of solution

2. Calorimetry

There are two energy flows in this reaction.

q₁ = heat from reaction

q₂ = heat to warm the water

The heat of solution is positive, because the water cooled down when the substance dissolved,

pla·gia·rism

/ˈplājəˌrizəm/

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noun

the practice of taking someone else's work or ideas and passing them off as one's own.

explanation:

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.