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3 years ago

How does a chemical reaction change from start to finish?

1 answer:

3 0

A physical Change, such as a state changing or dissolving, does not create a new substance, but a chemical change does.In a chemical reaction the atoms and molecules that interact with each other are called reactants.In a chemical change reaction the atoms and molecules produced by the reaction are called products.only the atoms present in the reactants can end up in the products. No new atoms are created and no atoms are destroyed. Reactants contact each other, bonds between atoms in the reactants are broken,and atoms rearrange and form new bonds to make new products.

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What is the functional group of a carboxylic acid?

Talja [164]

Answer:

A. Carbon double bonded to oxygen and a hydroxyl group (OH).

4 0

3 years ago

Given a magnesium value of 4.5mg/dL, what is the result in SI units?

DaniilM [7]

Answer:

$4.5x10^{-5}\frac{kg}{L}$

Explanation:

Hello!

In this case, since the density in the international system of units is given in terms of kg for the mass and L for the volume, we need to perform a process of units conversions from mg and dL to kg and L as show below:

$4.5\frac{mg}d{L}*\frac{1kg}{1x10^6mg} *\frac{10dL}{1L} \\\\4.5x10^{-5}\frac{kg}{L}$

Best regards!

8 0

3 years ago

if a gas sample has a pressure of 761 mmhg at 0.00°c by how much does the temperature have to decrease to lower the pressure to

Nady [450]

<h3>Answer:</h3>

272.43 K or -0.718°C

<h3>Explanation:</h3>

We are given;

The initial pressure,P1 as 761 mmHg

Initial temperature, T1 as 0.00°C which is equivalent to 273.15 K

Final pressure as 759 mmHg

We are required to calculate the final temperature;

According to pressure law, the pressure of a gas and absolute temperature are directly proportional at constant volume.

That is; Pα T

Therefore, at varying pressure and temperature,

$\frac{P1}{T1}=\frac{P2}{T2}$

To get final temperature;

$T2=\frac{P2T1}{P1}$

$T2=\frac{(759 mmHg)(273.15K)}{761 mmHg}$

$T2=272.43K$

Therefore, the final temperature will be 272.43 K or -0.718°C

6 0

3 years ago

Consider the reaction Mg₂Si(s) + 4 H₂O(ℓ) → 2 Mg(OH)₂(aq) + SiH₄(g). How many grams of silane gas (SiH₄) are formed if 25.0 g of

Neko [114]

Answer:

10.60 grams of silane gas are formed.

Explanation:

From the reaction:

Mg₂Si(s) + 4H₂O(l) → 2Mg(OH)₂(aq) + SiH₄(g)

We know that the limiting reactant is Mg₂Si, so to find the mass of SiH₄ formed we need to calculate the number of moles of Mg₂Si:

$\eta_{Mg_{2}Si} = \frac{m_{Mg_{2}Si}}{M_{Mg_{2}Si}}$

Where:

m: is the mass of Mg₂Si = 25.0 g

M: is the molar mass of Mg₂Si = 76.69 g/mol

$\eta_{Mg_{2}Si} = \frac{m_{Mg_{2}Si}}{M_{Mg_{2}Si}} = \frac{25.0 g}{76.69 g/mol} = 0.33 moles$

Now, the stoichiometric relation between Mg₂Si and SiH₄ is 1:1 so:

$\eta_{Mg_{2}Si} = \eta_{SiH_{4}} = 0.33 moles$

Finally, the mass of SiH₄ is:

$m_{SiH_{4}} = \eta_{SiH_{4}}*M_{SiH_{4}} = 0.33 moles*32.12 g/mol = 10.60 g$

Therefore, 10.60 grams of silane gas are formed.

I hope it helps you!

3 0

3 years ago

You are trying to determine the specific heat of a metal. You heat the 97 g piece of metal to 100 °C and place it in a calorimet

Brut [27]

Answer : The specific heat of the metal is, $0.658J/g^oC$

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

$q_1=-q_2$

$m_1\times c_1\times (T_f-T_1)=-m_2\times c_2\times (T_f-T_2)$

where,

$c_1$ = specific heat of metal = ?

$c_2$ = specific heat of water = $4.18J/g^oC$

$m_1$ = mass of metal = 97 g

$m_2$ = mass of water = 122 g

$T_f$ = final temperature of mixture = $28.9^oC$

$T_1$ = initial temperature of metal = $100^oC$

$T_2$ = initial temperature of water = $20.0^oC$

Now put all the given values in the above formula, we get

$97g\times c_1\times (28.9-100)^oC=-122g\times 4.18J/g^oC\times (28.9-20.0)^oC$

$c_1=0.658J/g^oC$

Therefore, the specific heat of the metal is, $0.658J/g^oC$

8 0

4 years ago