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HACTEHA [7]
3 years ago
6

After completing an experiment to determine gravimetrically the percentage of water in a hydrate, a student reported a value of

38 percent. The correct value for the percentage of water in the hydrate is 51 percent. Which of the following is the most likely explanation for this difference?
a) Strong initial heating caused some of the hydrate sample to splatter out b) The dehydrated sample absorbed moisture after heating c) The amount of the hydrate sample used was too small d) The crucible was not heated to constant mass before use e) Excess heating caused the dehydrated sample to decompose
Chemistry
1 answer:
SIZIF [17.4K]3 years ago
6 0

Answer:

b) The dehydrated sample absorbed moisture after heating

Explanation:

a) Strong initial heating caused some of the hydrate sample to splatter out.

This will result in a higher percent of water than the real one, because you assume in the calculation that the splattered sample was only water (which in not true).

b) The dehydrated sample absorbed moisture after heating.

Usually inorganic salts may absorbed moisture from the atmosphere so this will explain the 13% difference between calculated water percent the real content of water in the hydrate.

c) The amount of the hydrate sample used was too small.

It will create some errors but they do not create a difference of 13% difference as stated in the problem.

d) The crucible was not heated to constant mass before use.

Here the error is small.

e) Excess heating caused the dehydrated sample to decompose.

Usually the inorganic compounds are stable in the temperature range of this kind of experiments. If you have an organic compound which retain water molecules you may decompose the sample forming volatile compounds which will leave crucible so the error will be quite high.

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Describe the measurements necessary to find the average speed of a moving train
pshichka [43]

Answer:

use the rule of speed

Explanation:

speed =distance over time

3 0
2 years ago
How many grams of nickel (+2) are required to replace all of the silver when 15.55 grams of AgNO3 are present?
Karolina [17]

2AgNO3 + Ni2+  = Ni(NO3)2 + 2Ag<span>+</span>

From the reaction, it can be seen that AgNO3 and Ni2+ has following amount of substance relationshep:

n(AgNO3):n(Ni)=2:1

From the relationshep we can determinate requred moles of Ni2+:

n(AgNO3)=m/M= 15.5/169.87=0.09 moles

So, n (Ni)=n(AgNO3)/2=0.045 moles

Finaly needed mass of Ni2+ is:

m(Ni2+)=nxM=0,045x58.7=2.64g

8 0
3 years ago
Yeast converts glucose to ethanol and carbon dioxide during a process known as anaerobic fermentation. The chemical reaction is
Korolek [52]

Answer:

102g

Explanation:

To find the mass of ethanol formed, we first need to ensure that we have a balanced chemical equation. A balanced chemical equation is where the number of atoms of each element is the same on both sides of the equation (reactants and products). This is useful as only when a chemical equation is balanced, we can understand the relationship of the amount (moles) of reactant and products, or to put it simply, their relationship with one another.

In this case, the given equation is already balanced.

\tex{C_6H_{12}O_6} \longrightarrow 2 \ C_2H_6O + 2 \ CO_2

From the equation, the amount of ethanol produced is twice the amount of yeast present, or the same amount of carbon dioxide produced. Do note that amount refers to the number of moles here.

Mole= Mass ÷Mr

Mass= Mole ×Mr

<u>Method 1: using the </u><u>mass of glucose</u>

Mr of glucose

= 6(12) +12(1) +6(16)

= 180

Moles of glucose reacted

= 200 ÷180

= \frac{10}{9} mol

Amount of ethanol formed: moles of glucose reacted= 2: 1

Amount of ethanol

= 2(\frac{10}{9} )

= \frac{20}{9} mol

Mass of ethanol

= \frac{20}{9} \times[2(12)+6+16]

= \frac{20}{9}(46)

= 102 g (3 s.f.)

<u>Method 2: using </u><u>mass of carbon dioxide</u><u> produced</u>

Mole of carbon dioxide produced

= 97.7 ÷[12 +2(16)]

= 97.7 ÷44

= \frac{977}{440} mol

Moles of ethanol: moles of carbon dioxide= 1: 1

Moles of ethanol formed= \frac{977}{440} mol

Mass of ethanol formed

= \frac{977}{440} \times[2(12)+6+16]

= 102 g (3 s.f.)

Thus, 102 g of ethanol are formed.

Additional:

For a similar question on mass and mole ratio, do check out the following!

  • brainly.com/question/1685725
8 0
1 year ago
Given the partial equation:
Nikolay [14]

Answer : The balanced chemical equation in acidic medium will be,

IO_3^-(aq)+2Sn^{2+}(aq)+6H^+(aq)\rightarrow I^-(aq)+2Sn^{4+}(aq)+3H_2O(l)

Explanation :

Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

Rules for the balanced chemical equation in acidic solution are :

First we have to write into the two half-reactions.

Now balance the main atoms in the reaction.

Now balance the hydrogen and oxygen atoms on both the sides of the reaction.

If the oxygen atoms are not balanced on both the sides then adding water molecules at that side where the less number of oxygen are present.

If the hydrogen atoms are not balanced on both the sides then adding hydrogen ion (H^+) at that side where the less number of hydrogen are present.

Now balance the charge.

The given chemical reaction is,

IO_3^-(aq)+Sn^{2+}(aq)\rightarrow I^-(aq)+Sn^{4+}(aq)

The oxidation-reduction half reaction will be :

Oxidation : Sn^{2+}\rightarrow Sn^{4+}

Reduction : IO_3^-\rightarrow I^-

First balance the main element in the reaction.

Oxidation : Sn^{2+}\rightarrow Sn^{4+}

Reduction : IO_3^-\rightarrow I^-

Now balance oxygen atom on both side.

Oxidation : Sn^{2+}\rightarrow Sn^{4+}

Reduction : IO_3^-\rightarrow I^-+3H_2O

Now balance hydrogen atom on both side.

Oxidation : Sn^{2+}\rightarrow Sn^{4+}

Reduction : IO_3^-+6H^+\rightarrow I^-+3H_2O

Now balance the charge.

Oxidation : Sn^{2+}\rightarrow Sn^{4+}+2e^-

Reduction : IO_3^-+6H^++4e^-\rightarrow I^-+3H_2O

The charges are not balanced on both side of the reaction. Thus, we are multiplying oxidation reaction by 2 and the adding both equation, we get the balanced redox reaction.

Oxidation : 2Sn^{2+}\rightarrow 2Sn^{4+}+4e^-

Reduction : IO_3^-+6H^++4e^-\rightarrow I^-+3H_2O

The balanced chemical equation in acidic medium will be,

IO_3^-(aq)+2Sn^{2+}(aq)+6H^+(aq)\rightarrow I^-(aq)+2Sn^{4+}(aq)+3H_2O(l)

5 0
3 years ago
10.0 grams of water are heated during the preparation of a cup of coffee 1.0x 103 j of the heat are added to the water. which is
katovenus [111]

<u>Answer:</u> The final temperature of the coffee is 43.9°C

<u>Explanation:</u>

To calculate the final temperature, we use the equation:

q=mC(T_2-T_1)

where,

q = heat released = 1.0\times 10^3J=1000J

m = mass of water = 10.0 grams

C = specific heat capacity of water = 4.184 J/g°C

T_2 = final temperature = ?

T_1 = initial temperature = 20°C

Putting values in above equation, we get:

1000J=10.0g\times 4.184J/g^oC\times (T_2-20)\\\\T_2=43.9^oC

Hence, the final temperature of the coffee is 43.9°C

6 0
3 years ago
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