Phresh's Chemistry Questions

[the.watchman]

they assumed there was 250 ml of the solution.

Yep that looks right!
Good job superflya

[Phresh]

A student noted that her 50 mL burette was dirty and that droplets of liquid stuck to the inside surface of the tube. She decided to investigate if this would affect the burette’s accuracy. She filled the burette to the zero mark and drained a 50.00 mL titre into a flask that had previously been weighed. The flask was weighed again and the mass of water calculated. The student then calculated the volume of water by assuming that the density of water is 1.000 00 g mL–1. This procedure was repeated another four times. The masses of water for the five trials were 49.95 g, 49.93 g, 49.90 g, 49.93 g and 49.92 g.

(a)What is the average mass of the five water samples?

I got 49.93g, but answer says 49.63g. Can someone please confirm?

AND

(b)Calculate the average volume of these samples.
Answer says 50.00mL

Thanks

[Phresh]

bump

[Edmund]

I would say it is 49.93g for part a

[Studyinghard]

if a) is 49.93 then b) being 50 also sounds right because d = v/m. that formula gives you 50ml when rounded up.

[Phresh]

TY

Simple yr 11 stuff

What is the number of electrons of Mg^2+  A=24 Z=12.

Is the number of electrons the same as the number of protons..? Is this always true. I heard this is true when the element is 'neutral' (eg carbon)

[the.watchman]

It would be for a neutral atom, but for ions, 'subtract' the charge, so has 12-2=10 electrons