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3 years ago

What has the same number of valence electrons in the outermost shell?

Chemistry

1 answer:

algol [13]3 years ago

4 0

Answer:

Groups

Explanation:

Elements with the same number of valence electrons are found in the same column(group) of the Periodic Table.

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Helen adjusts the armature of an electric generator by increasing the number of coils around the iron core. what is helen most l

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Increase the amount of current

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3 years ago

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Which one is an accurate description of an erosion?

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the process of eroding or being eroded by wind, water, or other natural agents

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3 years ago

Water is flowing in a pipe with a mass flow rate of 100.0 lb/h (M water H,O=18.016). What is the (i) Molar flow rate of H20 (gmo

Arada [10]

Answer:

i) 0,7 molH20/s

ii)11,2 g O/s

iii)1,4 g H/s

Explanation:

i) To find the molar flow rate of water, we just convert the mass of water to moles of water using its molecular weight(g/mol) and changing to the proper units (lb to grames and hours to seconds):

$100 \frac{lb}{h}*\frac{453,5g}{1 lb}*\frac{1molH20}{18,016g}*\frac{1h}{3600s}=0,7\frac{molH20}{s}$

ii) Now we just consider the oxygen in the water stream (for 1 mole of water there is 1 mole of oxygen):

$100\frac{lb}{h} *\frac{453,5g}{1lb}*\frac{1 molH20}{18,016g}*\frac{1molO}{1molH20}*\frac{16gr}{1molO}*\frac{1h}{3600s}=11,2\frac{gO}{s}$

iii)Just considering the hydrogen in the stream (for 1 mole of water there is 2 moles of hydrogen):

$100\frac{lb}{h} *\frac{453,5g}{1lb}*\frac{1 molH20}{18,016g}*\frac{2molH}{1molH20}*\frac{1gr}{1molH}*\frac{1h}{3600s}=1,4\frac{gH}{s}$

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3 years ago

When cream mixes with coffee, is this a chemical or physical change?

svlad2 [7]

It is a physical change when cream mixes with coffee, it changes the color of the coffee. When you add more or less cream there is a color change depending on the consistency of cream. The properties are not changes and a no new compound is formed as in chemical change with a reaction of two compounds, a new compound is formed with different properties. So it is a physical change.

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3 years ago

The rate of disappearance of HBr in the gas phase reaction2HBr(g) → H2(g) + Br2(g)is 0.301 M s-1 at 150°C. The rate of appearanc

jok3333 [9.3K]

Answer: 0.151

Explanation:

Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

$2HBr(g)\rightarrow H_2(g)+Br_2(g$

The rate in terms of reactants is given as negative as the concentration of reactants is decreasing with time whereas the rate in terms of products is given as positive as the concentration of products is increasing with time.

$Rate=-\frac{1d[HBr]}{2dt}=+\frac{1d[H_2]}{2dt}=+\frac{1d[Br_2]}{dt}$

Given: $-\frac{d[HBr]}{dt}]=0.301$

Putting in the values we get:

$\frac{0.301}{2}=+\frac{1d[Br_2]}{dt}$

$+\frac{1d[Br_2]}{dt}=0.151$

Thus the rate of appearance of $Br_2$ is 0.151

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3 years ago