Answer:
5.83 g
Explanation:
First, you must start with a balanced equation so you can see the mole ratios.
NaOH + H₃BO₃ --> NaBO₂ + 2H₂O
You can see that it takes 1 mole of sodium hydroxide to form 1 mole of sodium borate. 1:1 ratio
Now you must calculate how many moles of NaOH 35.47 g equals.
Na = 22.99 amu
O = 15.99 amu
H = 1.008 amu
NaOH = 39.997 amu
35.47 g ÷ 39.997 amu = 0.08868 moles of NaOH
Since it's a 1:1 ratio, the same number of moles of NaBO₂ is created. Now you must convert moles to grams.
Na = 22.9 amu
B = 10.81 amu
2 O = 31.998 amu
NaBO₂ = 65.798 amu
0.08868 moles x 65.798 = 5.83 g
Answer: 1709.4 Joules
Explanation:
The quantity of Heat Energy (Q) released on cooling a heated substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)
Thus, Q = MCΦ
Since Q = ?
M = 18.5 grams
Recall that the specific heat capacity of copper C = 0.385 J/g.C
Φ = 285°C - 45°C = 240°C
Then, Q = MCΦ
Q = 18.5grams x 0.385 J/g.C x 240°C
Q = 1709.4 Joules
Thus, 1709.4 Joules is released when copper is cooled.
ok so this was really confusing, but i think i know the answer. D. ...hairy and ancient hermit crabs and swift, darting minnows and sometimes a
crumbling sand dollar.
I would say that you should wear a lab coat, safety goggles, and gloves
when the teacher says so - not everything in a lab is dangerous, so
there is no need to always wear these. But when the teacher says you
should - then you should.
