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Naddika [18.5K]

3 years ago

11

Một chất phóng xạ có chu kỳ bán huỷ là 10 năm, Hỏi bao nhiêu năm thì lượng phóng xạcòn 10%. Cho biết phản ứng phân hủy chất phón

g xạ là phản ứng bậc

1 answer:

lys-0071 [83]3 years ago

7 0

Answer:

what

Explanation:

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A sample of oxalic acid (a diprotic acid of the formula H2C2O4) is dissolved in enough water to make 1.00 L of solution. A 100.0

OleMash [197]

<u>Answer:</u> The mass of original oxalic acid sample is 6.75 grams

<u>Explanation:</u>

To calculate the concentration of acid, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is $H_2C_2O_4$

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is NaOH.

We are given:

$n_1=2\\M_1=?M\\V_1=100.0mL\\n_2=1\\M_2=0.750M\\V_2=20.0mL$

Putting values in above equation, we get:

$2\times M_1\times 100.0=1\times 0.750\times 20.0\\\\M_1=\frac{1\times 0.750\times 20.0}{2\times 100.0}=0.075M$

To calculate the mass of solute, we use the equation used to calculate the molarity of solution:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (in L)}}$

Given mass of oxalic acid = ? g

Molar mass of oxalic acid = 90 g/mol

Molarity of solution = 0.075 M

Volume of solution = 1.00 L

Putting values in above equation, we get:

$0.075M=\frac{\text{Mass of oxalic acid}}{90g/mol\times 1L}\\\\\text{Mass of oxalic acid}=(0.075\times 90\times 1)=6.75g$

Hence, the mass of original oxalic acid sample is 6.75 grams

7 0

3 years ago

How many moles of chlorine gas would occupy a volume of 35.5 L at a pressure of 100.0 kPa and a

Nikolay [14]

Answer:

this was the last of .the last 555543 years of 55my in

Explanation:

t

4 0

3 years ago

A water treatment plant applies chlorine for disinfection so that 10 mg/L chlorine is achieved immediately after mixing. The vol

Vlada [557]

<u>Answer:</u> The mass of chlorine needed by the plant per day is $9.4625\times 10^8mg$

<u>Explanation:</u>

We are given:

Volume o water treated per day = 25,000,000 gallons

Converting this volume from gallons to liters, we use the conversion factor:

1 gallon = 3.785 L

So, $\frac{3.785L}{1\text{ gallon}}\times 25,000,000\text{ gallons}=9.4625\times 10^7L$

Amount of chlorine applied for disinfection = 10 mg/L

Applying unitary method:

For 1 L of water, the amount of chlorine applied is 10 mg

So, for $9.4625\times 10^7L$ of water, the amount of chlorine applied will be $\frac{10mg}{1L\times 9.4625\times 10^7L}=9.4625\times 10^8mg$

Hence, the mass of chlorine needed by the plant per day is $9.4625\times 10^8mg$

6 0

3 years ago

Which color of light has the greatest energy

ozzi

Answer:

violet

Explanation:

Waves with a short wavelength have the most energy. Red waves have a relatively long wavelength (in the 700 nm range), and violet waves are much shorter - roughly half that. Because violet waves have the shortest wavelength of the visible light spectrum, they carry the most energy (google)

4 0

3 years ago

Explain how changing the concentration The enthalpy change for the reaction, 3CO (g) 2Fe2O3 (s) Imported Asset Fe(s) 3CO2 (g), c

ycow [4]

<u>Answer:</u> For the given equation, only iron has the value of $\Delta H_f$ equal to 0 kJ.

<u>Explanation:</u>

Enthalpy change is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as $\Delta H^o$

The equation used to calculate enthalpy change is of a reaction is:

$\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f(product)]-\sum [n\times \Delta H^o_f(reactant)]$

For the given chemical reaction:

$3CO(g)+2Fe_2O_3(s)\rightarrow Fe(s)+3CO_2(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(1\times \Delta H^o_f_{(Fe(s))})+(3\times \Delta H^o_f_{(CO_2(g))})]-[(3\times \Delta H^o_f_{(CO(g))})+(2\times \Delta H^o_f_{(Fe_2O_3(s))})]$

The enthalpy of formation for the substances present in their elemental state is taken as 0.

Here, iron is present in its elemental state which is solid.

Hence, for the given equation, only iron has the value of $\Delta H_f$ equal to 0 kJ.

7 0

3 years ago