Which will evaporate first: a bowl of water that is heavily salted, or a bowl that isn't?

[Acme]

Analogue doesn't work any more; rain is digital now.

Damn! Missed the bus again.

 

Was out in the garden and felt a little more of that digital rain. Cover is in place, temperature 77ºF, relative humidity 49%, and barometric pressure 29.57 inches of mercury and steady.

[Acme]

Report on 2 measurements today and a photo of the current salt rind on the jar. The rind was absent this morning when I took the first measurement. During the interval of today's measures, when the Sun was out, the rate of evaporation was equal, i.e. both levels dropped 3mm.

 

☼check Monday August 3 10:45am 96 hrs/4d: salt down 3.3 cm / plain down 3.5 cm

Relative humidity 51%, temperature 67º, barometric pressure 29.65 inches of mercury

 

☼check Monday August 3 4:00pm 101.25 hrs : salt down 3.6 cm / plain down 3.8 cm

Relative humidity 42%, temperature 82º, barometric pressure 29.58 inches of mercury

 

[Acme]

Report on 2 measurements today. No photo of the current salt rind, but very little remained this morning and now it is larger than any time previous. [Will get photo ASAP] During the interval of today's measures, when the Sun was out, the rate of evaporation was higher for the salted water than for the pure water, i.e. the salted water level dropped 3mm and the pure water level dropped 2mm.

 

☼check Tuesday August 4 11:40am 121 hr/~5d : salt down 3.7 cm / plain down 4.0 cm

Relative humidity 52%, temperature 69º, barometric pressure 29.70 inches of mercury

 

☼check Tuesday August 4 4:00pm 125 hr : salt down 4.0 cm / plain down 4.2 cm

Relative humidity 40%, temperature 82º, barometric pressure 29.62 inches of mercury

 

Here's the photo. The jars are still in full sun, but I positioned myself to shade this jar for a decent exposure by the camera.

 

Edited August 4, 2015 by Acme

[Acme]

Update: The Sun has set and the solution has reached the saturation point with some nice cubic crystals formed on the bottom of the jar. The crystals on the surface formed on some dust and no-see-ums that have fallen in. Photo below.

 

☼check Tuesday August 4 8:15pm 129.25 hr : salt down 4.2 cm / plain down 4.5 cm

Relative humidity 45%, temperature 71º, barometric pressure 29.64 inches of mercury

 

[Acme]

Report on 2 measurements today and a photograph of the jar with salted water.

 

☼check Wednesday August 5 10:45pm 144hr/6d: salt down 4.3 cm / plain down 4.6 cm

Relative humidity 53%, temperature 63º, barometric pressure 29.81 inches of mercury

 

☼check Wednesday August 5 07:15pm 152.5 hr : salt down 4.7 cm / plain down 5.0 cm

Relative humidity 46%, temperature 75º, barometric pressure 29.73 inches of mercury

 

[Acme]

Report on 5 measurements and conclusion of experiment.

 

☼check Thursday August 6 10:45am 168hr/7d : salt down 4.8 cm / plain down 5.05cm

Relative humidity 35%, temperature 66º, barometric pressure 29.81 inches of mercury

 

☼check Thursday August 6 7:45pm 177hr : salt down 5.4 cm / plain down 5.6 cm

Relative humidity 48%, temperature 77º, barometric pressure 29.64 inches of mercury

 

☼check Friday August 7 10:45am 192hr/8d : salt down 5.4 cm / plain down 5.7 cm

Relative humidity 56%, temperature 67º, barometric pressure 29.62 inches of mercury

 

☼check Friday August 7 12:33pm 193.75hr : salt down 5.7 cm / plain down 6.0 cm dry

Relative humidity 51%, temperature 71º, barometric pressure 29.58 inches of mercury

 

☼check Friday August 7 2:45pm 196hr : salt down 5.9 cm dry/ plain down 6.0 cm dry

Relative humidity 39%, temperature 82º, barometric pressure 29.54 inches of mercury

 

Summary:

 

Start Thursday July 30 10:45am 0 hours : both full 6.0 cm

check Thursday July 30 3:45pm 5 hours : salt down .24cm / plain down .24cm

check Friday July 31 8:00pm 33 hours : salt down 2.1 cm / plain down 2.1 cm

check Saturday Augst 1 4:00pm 53 hours : salt down 3.0 cm / plain down 3.0 cm

check Sunday Augst 2 10:45am 72 hr/3d : salt down 3.1 cm / plain down 3.2 cm

check Monday Augst 3 10:45am 96 hr/4d : salt down 3.3 cm / plain down 3.5 cm

check Monday Augst 3 4:00pm 101.25hr : salt down 3.6 cm / plain down 3.8 cm

check Tuesday Augst 4 11:40am 121 hr/5d : salt down 3.7 cm / plain down 4.0 cm

check Tuesday Augst 4 4:00pm 125 hr : salt down 4.0 cm / plain down 4.2 cm

check Tuesday Augst 4 8:15pm 129.25 hr : salt down 4.2 cm / plain down 4.5 cm

check Wednsday Augst 5 10:45am 144hr/6d : salt down 4.3 cm / plain down 4.6 cm

check Wednsday Augst 5 7:15pm 152.5hr : salt down 4.7 cm / plain down 5.0 cm

check Thursday Augst 6 10:45pm 168hr/7d : salt down 4.8 cm / plain down 5.05cm

check Thursday Augst 6 7:45pm 177hr : salt down 5.4 cm / plain down 5.6 cm

check Friday Augst 7 10:45am 192hr/8d : salt down 5.4 cm / plain down 5.7 cm

check Friday Augst 7 12:33pm 193.75hr : salt down 5.7 cm / plain down 6.0 cm dry

check Friday Augst 7 2:45pm 196hr : salt down 5.9 cm dry

 

Conclusion

While in sunlight the rate of evaporation is virtually equal for the salted and unsalted water, with the differing rates occurring principally overnight and/or when the precipitated salt rind is in contact with the water.

 

Note: Any typos I blame on others but let me know and I'll make an effort to correct them & punish the offender(s).

Edited August 7, 2015 by Acme