1) An endothermic reaction is a reaction where heat is "absorbed" and the surrounding area is cooled. An example of an endothermic reaction is the classic baking soda and vinegar reaction. The mixture gets cold.
An exothermic reaction is one which gives off heat, such as burning, which is itself a chemical reaction.
2) (I don't actually know this one but i hope i helped with number one)
Answer:
C. Solution B is less acidic than solution A.
Answer:
Answer is Object 2 (which has a density of 1.9 g/cm³).
Explanation;
When object is floating, the weight of that object is less than the up thrust on it.
When an object fully submerged and floating, then the weight of that object is equal to the up thrust on it.
This is known as the Archemide's principle.
Both up thrust and weight depends on the density. Hence, if the density of the solution is high, then the up thrust also high. If the density high, the the weight of the object also high.
Hence, to sink the object in water, that object should be denser than water. Hence, answer is object 3 which has a higher density than water.
Explanation:
For all three questions, we will use the fact that
- molarity = (moles of solute)/(liters of solution)
1) For 175 mL of solution at 0.203 M, this means that:
- 0.203 = (moles of solute)/0.175
- moles of solute = 0.035523 mol
Considering the hydrochloric acid solution, if we have 0.035523 mol, then:
- 6.00 = 0.035523/(liters of solution)
- liters of solution = 0.035523/6.00 = 0.0059205 = <u>5.92 mL (to 3 sf)</u>
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2) If there is 20.3 mL = 0.0203 L, then:
- 8.20 = (moles of solute)/0.0203
- moles of solute = 0.16646 mol
This means that the molarity of the diluted solution is:
- 0.16646/(0.200) = <u>0.832 M (to 3 sf)</u>
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3) If we need 1.50 L of 0.700 M solution, then:
- 0.700 = (moles of solute)/1.50
- moles of solute = 1.05 mol
Considering the 9.36 M acid solution, from which we need 1.05 mol of perchloric acid from,
- 9.36 = 1.05/(liters of solution)
- liters of solution = 1.05/9.36, which is 0.11217948717949 L, or <u>112 mL (to 3 sf)</u>
