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3 years ago

Review

Chemistry

1 answer:

ZanzabumX [31]3 years ago

7 0

Answer:

1. Gold is valuable because of its high quality physical and chemical properties

2. The gold mines where the state's property in both Egyptian and Roman civilizations

3. The elixir of life is akin to the philosopher stone. It is a chemical portion that when drank, grants eternal life

4. The contribution of alchemists to modern chemistry, includes the formulation of the first ideological periodic table, the distillation process, metalworking, gunpowder, glass, ink, paints, cosmetics and many other innovations

Explanation:

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A19.0g sample of brass, which has a specific heat capacity of 0.375·J*g^−1°C−, is dropped into an insulated container containing

djverab [1.8K]

Answer:

The final temperature is 20.3 °C

Explanation:

Considering that:-

Heat gain by water = Heat lost by brass

Thus,

$m_{water}\times C_{water}\times (T_f-T_i)=-m_{brass}\times C_{brass}\times (T_f-T_i)$

Where, negative sign signifies heat loss

Or,

$m_{water}\times C_{water}\times (T_f-T_i)=m_{brass}\times C_{brass}\times (T_i-T_f)$

For water:

Mass = 300.0 g

Initial temperature = 20.0 °C

Specific heat of water = 4.184 J/g°C

For brass:

Mass = 19.0 g

Initial temperature = 81.7 °C

Specific heat of water = 0.375 J/g°C

So,

$300.0\times 4.184\times (T_f-20.0)=19.0\times 0.375\times (81.7-T_f)$

$1255.2T_f-25104=582.1125-7.125T_f$

$1262.325T_f=25686.1125$

$T_f = 20.3\ ^0C$

Hence, the final temperature is 20.3 °C

6 0

3 years ago

Given R

icang [17]

Answer:

Explanation:

there are a certain amount of atoms

6 0

3 years ago

Which of the above solutions could be used to remove lead from lead (II) nitrate?

alisha [4.7K]

Ni solution could be used to remove lead from lead (II) nitrate.

Explanation:

The removal of lead from lead nitrate will take place by displacement reaction.

In displacement reaction less reactive element is displaced by more reactive element form it compound.

The reactivity is decided by the placement of metal in the activity series.

A metal which is at higher position in the activity series will be able to displace the metal or element having lower position.

From the options given we will check their position in the activity series in comparison to Pb

Cu is lower in series than Pb hence cannot displace.

Hg is placed lower in the series than Pb hence cannot displace Pb.

Ag is placed lower than Pb in the series hence cannot displace Pb.

Ni is placed above the Pb in activity series hence can displace lead.

8 0

3 years ago

Assume that a milliliter of water contains 20 drops. How long, in hours, will it take you to count the number of drops

garri49 [273]

Answer:

126.18 hr

Explanation:

Data given:

1 mL of water = 20 drops

count rate = 10 drops/s

time in hours for one gallon = ?

Solution:

First we calculate number of mL (milliliter) of water in gallon

As we know

1 gallon = 3785.4 mL

As,

1 galon consist of 3785.4 mL of water, so now we count number of drops that contain 3785.4 mL of water

As we Know 1 mL water contain 20 drops then 3785.4 mL of water contain how many drops:

Apply unity formula

1 mL water ≅ 20 drops

3785.4 mL water ≅ X drops

Do cross multiplication

X drops of water = 20 drops x 3785.4 mL / 1 mL

X drops of water = 75708 drops

So, we come to know that one gallon contain 75708 drops of water and we have to calculate the time in hour to count these drops

First we calculate time in seconds

As we Know 10 drops water count in one second then how many seconds it will take to count 75708 drops

Apply unity formula

1 second ≅ 10 drops

X second ≅ 75708 drops

Do cross multiplication

X second = 1 second x 75708 drops / 10 drops

X second = 7570.8 second

So it take 7570.8 second to count 1 gallon water drops

Now convert seconds to hours

As,

60 seconds = 1 hr

7570.8 second = 7570.8 / 60 = 126.18 hr

So it take 126.18 hr to count 1 gallon water drops.

6 0

4 years ago

Why don't rockets need air to stay up, like planes do?

forsale [732]

Part of a rocket's propulsion system includes a chemical oxidizer, either in the form of liquid oxygen, the solid ammonium perchlorate, or the propulsion/oxidizer mixture Hydrazine. No outside source of oxygen is needed.

Steering is accomplished by "gimbaled" rocket nozzles which change the direction of the blast to keep the rocket on course. Once in space and in orbit, slight changes in orientation is made by small rockets placed around the craft that spurt little gas jets to nudge the craft into the desired position.

7 0

3 years ago