What unknown quantity can be calculated after performing a titration? a. volume c. mass b. concentration d. density

If you combine 230.0 mL 230.0 mL of water at 25.00 ∘ C 25.00 ∘C and 120.0 mL 120.0 mL of water at 95.00 ∘ C, 95.00 ∘C, what is t

Thepotemich [5.8K]

Answer: The final temperature of the mixture is 49°C

Explanation:

To calculate the mass of water, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

For cold water:

Density of cold water = 1 g/mL

Volume of cold water = 230.0 mL

Putting values in above equation, we get:

$1g/mL=\frac{\text{Mass of water}}{230.0mL}\\\\\text{Mass of water}=(1g/mL\times 230.0mL)=230g$

For hot water:

Density of hot water = 1 g/mL

Volume of hot water = 120.0 mL

Putting values in above equation, we get:

$1g/mL=\frac{\text{Mass of water}}{120.0mL}\\\\\text{Mass of water}=(1g/mL\times 120.0mL)=120g$

When hot water is mixed with cold water, the amount of heat released by hot water will be equal to the amount of heat absorbed by cold water.

$Heat_{\text{absorbed}}=Heat_{\text{released}}$

The equation used to calculate heat released or absorbed follows:

$Q=m\times c\times \Delta T=m\times c\times (T_{final}-T_{initial})$

$m_1\times c\times (T_{final}-T_1)=-[m_2\times c\times (T_{final}-T_2)]$ ......(1)

where,

q = heat absorbed or released

$m_1$ = mass of hot water = 120 g

$m_2$ = mass of cold water = 230 g

$T_{final}$ = final temperature = ?°C

$T_1$ = initial temperature of hot water = 95°C

$T_2$ = initial temperature of cold water = 25°C

c = specific heat of water = 4.186 J/g°C

Putting values in equation 1, we get:

$120\times 4.186\times (T_{final}-95)=-[230\times 4.186\times (T_{final}-25)]$

$T_{final}=49^oC$

Hence, the final temperature of the mixture is 49°C

4 0

3 years ago

An unknown compound contains only C , H , and O . Combustion of 4.20 g of this compound produced 10.3 g CO 2 and 4.20 g H 2 O .

vodomira [7]

Answer:

C4H8O

Explanation:

We can get the answer through calculations as follows.

From the mass of carbon iv oxide produced, we can get the number of moles of carbon produced. We first divide the mass by the molar mass of carbon iv oxide. The molar mass of carbon iv oxide is 44g/mol

The number of moles of carbon iv oxide is 10.3/44 = 0.2341

Since there is only one carbon atom in CO2, the number of moles of carbon is same as above

The mass of carbon in the compound is simply the number of moles multiplied by the atomic mass unit. The atomic mass unit of carbon is 12. The mass of carbon in the compound is thus 12 * 0.2341= 2.8091

From the number of moles of water, we can get the number of moles of hydrogen. To get the number of moles of water, we need to divide the mass of water by its molar mass. Its molar mass is 18g/mol. The number of moles here is thus 4.2/18 = 0.2333

But there are 2 atoms of hydrogen in 1 mole of water and thus, the number of moles of hydrogen is 2 * 0.2333 = 0.4667 moles

The mass of hydrogen is thus 0.4667* 1 = 0.4667

The mass of oxygen equals the mass of the compound minus that of hydrogen and that of carbon.

= 4.2 - 0.4667 - 2.8091 = 0.9242

The number of moles of oxygen is the mass of oxygen divided by its atomic mass unit.

That equals 0.9242/16 = 0.0577625 moles

The empirical formula can be obtained by dividing the number of moles of each by the smallest which is that of oxygen

H = 0.4667/0.0577625 = 8

O = 0.0577625/0.0577625 = 1

C = 0.2341/0.0577625 = 4

The empirical formula is thus C4H8O

5 0

2 years ago

What do you observe on the filter paper strip after 2 to 3 hours?

just olya [345]

It would have filtered already within the time frame of 2 to 3 hours because of the molecular injection ignited by the co2 within the strip so you would observe the UNDERSIDE OF THE PAPER and the molecular tear within it

8 0

2 years ago

2. Acidity and basicity of solutions of common substances at 25 ºC: a. Calculate the pH of a sample of lemon juice with [H+ ] =

Lelechka [254]

Answer:

a. The pH of a sample of lemon juice with [H⁺] = 3.8*10⁻⁴ M is 3.4, indicating acidity.

b. The pH of a commonly available window-cleaning solution with [OH⁻] = 1.9*10⁻⁶ M is 8.28, indicating basicity.

c. The [H⁺] is 1.74*10⁻⁴ M.

d. The [OH⁻] is 1.51*10⁻⁵ M.

Explanation:

pH is a measure of acidity or alkalinity that indicates the amount of hydrogen [H⁺] or hydronium [H₃O⁺] ions present in a solution or substance. Mathematically the pH is the negative logarithm of the molar concentration of the hydrogen or proton ions (H⁺) or hydronium ions (H₃O⁺):

pH= -log₁₀ [H⁺]= -log₁₀ [H₃O⁺] or pH= -log [H⁺]= -log [H₃O⁺]

The pH scale ranges from 0 to 14. Values less than 7 indicate the acidity range and those greater than 7 indicate alkalinity or basicity. Value 7 is considered neutral.

Case a

You know [H⁺]= 3.8*10⁻⁴ M. Then:

pH= -log (3.8*10⁻⁴)

pH=3.42

The pH of a sample of lemon juice with [H⁺] = 3.8*10⁻⁴ M is 3.4, indicating acidity.

Case b

Like pH, pOH (or OH potential) is a measure of the basicity or alkalinity of a solution.

The pOH indicates the concentration of hydroxyl ions [OH-] present in a solution:

pOH= -log₁₀ [OH⁻]= -log [OH⁻]

The pOH is related to the pH by the formula:

pH + pOH= 14

In this case you know [OH⁻]=1.9*10⁻⁶ M. Then: