Chemistry, 05.10.2019 11:00 yadi64

If 0.5 gramd of hcl is dissolved in 500 ml of solution what is the ph

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Salts are composed of positive and negative ions packed closely together in a crystal lattice. The crystal is held together by the ionic forces among oppositely charged particles in the solid. When a crystal of a salt is placed in water, the polar water molecules arrange their dipoles around the ions of the crystal in such a way as to attract the ions. For example, a positive ion at a corner of the crystal will be surrounded by a group of water molecules aiming the negative end of their dipoles at the positive ion. If the forces of attraction of the water molecules for the positive ion are larger than the ionic forces holding the ion in the crystal, then the ion will leave the crystal and enter solution. See Figure 15.2
8. Carbon dioxide is somewhat soluble in water, especially if pressurized (otherwise, the soda you may be drinking while studying Chemistry would be “flat”). Carbon dioxide’s solubility in water is approximately 1.5 g/L at 25°C under a pressure of approximately 1 atm. Although the carbon dioxide molecule overall is non-polar, that is because the two individual C–O bond dipoles cancel each other due to the linearity of the molecule. However these bond dipoles are able to interact with water, making CO2 more soluble in water than non-polar molecules such as O2 or N2 that do not possess individual bond dipoles.

Answer from: Quest

Answer: abeexplanation:

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.

Answer from: Quest

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements

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