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3 years ago

How can you tell that a precipitate has formed?

Chemistry

2 answers:

ladessa [460]3 years ago

7 0

Answer:

if a solid appears when mixing two liquids

Explanation:

i remember this question :D

Damm [24]3 years ago

6 0

^basically what they said

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What could happen if the chemists do not follow the exact formula for medications? (Give examples)

nataly862011 [7]

Answer:

qwe

Explanation:

wqe

3 0

3 years ago

The refining of aluminum from bauxite ore (which contains 50.% Al2O3 by mass) proceeds by the overall reaction 2Al2O3 + 3C → 4Al

iragen [17]

Answer:

18.9 x 10¹³ grams of Bauxite Ore

Explanation:

Al₂O₃ = 50% of Bauxite Ore

Al₂O₃ = 0.5 (Bauxite Ore)--------------------------------------- (1)

Overall reaction:

2Al₂O₃ + 3C → 4Al + 3CO₂--------------------------------------- (2)

[ Al= 27 , O=16, C=12]

From (2), 2 moles of Aluminium oxide (Al₂O₃) gives 4 moles of Aluminium

In terms of grams, we can say:

Al₂O₃ = [2(27) +3(16)]

= 54 +48

=102grams

2 moles of Al₂O₃ = 2 x102grams

=204grams

4 moles of Al = 4 x 27

=108 grams

So from (2):

204 grams of Al₂O₃ = 108 grams of Aluminium

x grams of Al₂O₃ = 5.0 x 10¹³grams of Aluminium

Calculating for x:

x = (204 x 5.0 x 10¹³)/ 108

= 9.44 x 10¹³ grams

So 9.44 x 10¹³ grams of pure bauxite (Bauxite) is required.

However the to calculate the quantity of raw bauxite, we use (1):

Bauxite ore = Pure Bauxite/0.5

= 9.44 x 10¹³ grams/0.5

= 18.88 x 10¹³ grams

≈ 18.9 x 10¹³ grams

8 0

3 years ago

Cobalt-60 is a strong gamma emitter that has a half- life of 5.26 yr. The co balt-60 in a radiotherapy unit must be replaced whe

Alenkasestr [34]

<u>Answer:</u> The sample of Cobalt-60 isotope must be replaced in January 2027

<u>Explanation:</u>

The equation used to calculate rate constant from given half life for first order kinetics:

$t_{1/2}=\frac{0.693}{k}$

where,

$t_{1/2}$ = half life of the reaction = 5.26 years

Putting values in above equation, we get:

$k=\frac{0.693}{5.26yrs}=0.132yrs^{-1}$

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}$

where,

k = rate constant = $0.132yr^{-1}$

t = time taken for decay process = ? yr

$[A_o]$ = initial amount of the sample = 100 grams

[A] = amount left after decay process = (100 - 75) = 25 grams

Putting values in above equation, we get:

$0.132=\frac{2.303}{t}\log\frac{100}{25}\\\\t=10.5yrs$

The original sample was purchased in June 2016

As, June is the 6th month of the year, which means the time period will be $2016+\frac{6}{12}=2016.5$

Adding the time in the original time period, we get:

$2016.5+10.5=2027$

Hence, the sample of Cobalt-60 isotope must be replaced in January 2027

3 0

4 years ago

Some activities that are generally considered to be work are not called work by scientists. Explain why.

Flura [38]

Answer:

Certain things we think of as hard work, such as writing an exam or carrying a heavy load on level ground, are not work as defined by a scientist. The scientific definition of work reveals its relationship to energy—whenever work is done, energy is transferred.

For work, in the scientific sense, to be done, a force must be exerted and there must be motion or displacement in the direction of the force.

5 0

2 years ago

1. Two boys balanced steady in a sea-saw game

anygoal [31]

Mutual

They are balanced steadily which means they’re at the same point

4 0

3 years ago

Read 2 more answers