What is the half life of an isotope that is 75% decayed after 16 days?

PLEASE HELPP!

Arada [10]

Answer:

18.18 C

Explanation:

m=55

C=0.45

Q=450zj

ch.temp=?

Q=mct

450 = (55)(.45)T

450 = 24.75

/24.75 = /24.75 (cancels out)

18.18 is the answer

6 0

3 years ago

Reactions

harina [27]

Answer:

answer in picture

Explanation:

7 0

3 years ago

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Use tabulated standard electrode potentials to calculate the standard cell potential for the following reaction occurring in an

SVETLANKA909090 [29]

Answer : The standard cell potential of the reaction is, -1.46 V

Explanation :

The given balanced cell reaction is,

$3Pb^{2+}(aq)+2Cr(s)\rightarrow 2Cr^{3+}(aq)+3Pb(s)$

Here, chromium (Cr) undergoes oxidation by loss of electrons and act as an anode. Lead (Pb) undergoes reduction by gain of electrons and thus act as cathode.

The standard values of cell potentials are:

Standard reduction potential of lead $E^0_{[Pb^{2+}/Pb]}=-0.13V$

Standard reduction potential of chromium $E^0_{[Cr^{3+}/Cr]}=1.33V$

Now we have to calculate the standard cell potential for the following reaction.

$E^0=E^0_{cathode}-E^0_{anode}$

$E^0=E^0_{[Pb^{2+}/Pb]}-E^0_{[Cr^{3+}/Cr]}$

$E^0=(-0.13V)-1.33V=-1.46V$

Therefore, the standard cell potential of the reaction is, -1.46 V

6 0

4 years ago

Write the balanced chemical equation for each of these reactions. Include phases.

Ket [755]

Answer: The chemical equations are given below.

Explanation:

For 1:

The chemical equation for the reaction of lead nitrate and sodium hydroxide follows:

$Pb(NO_3)_2(aq.)+2NaOH(aq.)\rightarrow Pb(OH)_2(s)+2NaNO_3(aq.)$

By Stoichiometry of the reaction:

1 mole of aqueous solution of lead nitrate reacts with 2 moles of aqueous solution of sodium hydroxide to produce 1 mole of solid lead hydroxide and 2 moles of aqueous solution of sodium nitrate.

For 2:

The chemical equation for the reaction of lead hydroxide and hydroxide ions follows:

$Pb(OH)_2(s)+2OH^-(aq.)\rightarrow [Pb(OH)_4]^{2-}(aq.)$

By Stoichiometry of the reaction:

1 mole of lead hydroxide reacts with 2 moles of aqueous solution of hydroxide ions to produce 1 mole of aqueous solution of tetra hydroxy lead (II) complex

Hence, the chemical equations are given above.

4 0

3 years ago

If you need to reverse the following reaction in order for it to be an intermediate reaction in a Hess's law problem, what would

Olin [163]

When reversing a given reaction, we simply change the sign of the standard enthalpy change value. Therefore, the reaction will become:
H₂O → H₂ + 0.5O₂, ΔH = 286kJ
This is because if a certain amount of energy is released when a reaction occurs, the same amount of energy must be supplied for the reaction to occur in the reverse direction.

4 0

3 years ago

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