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According to the equation below, how many moles of Ca(OH)2 are required to react with 1.36 mol H3PO4 to produce Ca3(PO4)2? 3Ca(O

allsm [11]

Answer: The amount of calcium hydroxide needed to react is 2.04 moles

Explanation:

We are given:

Moles of phosphoric acid = 1.36 moles

For the given chemical equation:

$3Ca(OH)_2+2H_3PO_4\rightarrow Ca_3(PO_4)_2+6H_2O$

By Stoichiometry of the reaction:

2 moles of phosphoric acid reacts with 3 moles of calcium hydroxide

So, 1.36 moles of phosphoric acid will react with = $\frac{3}{2}\times 1.36=2.04mol$ of calcium hydroxide

Hence, the amount of calcium hydroxide needed to react is 2.04 moles

3 0

3 years ago

The molar absorptivity of a tyrosine residue at 280 nm is 2000 M-1cm-1, while for tryptophan it is 5500 M-1cm-1. A protein has b

adelina 88 [10]

Answer:

There are 4 tryptophans in the protein.

Explanation:

According to question, protein contains one tyrosine residue and say x number of tryptophans.

Concentration of protein solution = 1.0 micromolar = $1.0\times 10^{-6} Molar$

Molar absorptivity of a protein solution : $\epsilon$

$\epsilon = \epsilon _{tyro}+\epsilon _{tryp}$

$=1\times 2000 M^{-1}cm^{-1}+x\times 5500 M^{-1}cm^{-1}$

Length of the cuvette = l = 1.0 cm

Absorbance of protein solution at 280 nm = A = 0.024

$A=\epsilon \times l\times c$ ( Beer-Lambert's law)

$0.024=(1\times 2000 M^{-1}cm^{-1}+x\times 5500 M^{-1}cm^{-1})\times 1 cm\times 1.0\times 10^{-6} M$

Solving for x :

x = 4

There are 4 tryptophans in the protein.

7 0

2 years ago

A gas has a volume of 5.00 L at 0°C. What final temperature, in degrees Celsius, is needed to change the volume of the gas to ea

Diano4ka-milaya [45]

Answer:

A = -213.09°C

B = 15014.85 °C

C = -268.37°C

Explanation:

Given data:

Initial volume of gas = 5.00 L

Initial temperature = 0°C (273 K)

Final volume = 1100 mL, 280 L, 87.5 mL

Final temperature = ?

Solution:

Formula:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume

T₂ = Final temperature

Conversion of mL into L.

Final volume = 1100 mL/1000 = 1.1 L

Final volume = 87.5 mL/1000 = 0.0875 L

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

T₂ = V₂T₁ / V₁

T₂ = 1.1 L × 273 K / 5.00 L

T₂ = 300.3 L.K / 5.00 K

T₂ = 60.06 K

60.06 K - 273 = -213.09°C

2)

V₁/T₁ = V₂/T₂

T₂ = V₂T₁ / V₁

T₂ = 280 L × 273 K / 5.00 L

T₂ = 76440 L.K / 5.00 K

T₂ = 15288 K

15288 K - 273 = 15014.85 °C

3)

V₁/T₁ = V₂/T₂

T₂ = V₂T₁ / V₁

T₂ = 0.0875 L × 273 K / 5.00 L

T₂ = 23.8875 L.K / 5.00 K

T₂ = 4.78 K

4.78 K - 273 = -268.37°C

4 0

2 years ago

Two completely different compounds may contain identical elements. True False

lesantik [10]

True.

For example: Sodium oxide and Nitric acid; both compounds contain oxygen.

7 0

3 years ago

Out of Br2 and NaBr which compound is more likely to be more soluble in CCl4

saul85 [17]

Br2 because it is non polar and so is CCl4 and like molecules dissolve like molecules therefore Br2 will dissolve in CCl4

6 0

3 years ago