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Mars2501 [29]
3 years ago
5

Is francium found in nature or lab?

Chemistry
1 answer:
ddd [48]3 years ago
8 0

Answer:

It was the last element first discovered in nature, rather than by synthesis. Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays

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What is the role of critical thinking in scientific process
laiz [17]

Answer:

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6 0
4 years ago
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What is water's density at 93 ∘C? Assume a constant coefficient of volume expansion. Express your answer with the appropriate un
Ganezh [65]

Answer:

982.5 kg/m³

Explanation:

When the temperature of a fluid increases, it dilates, and because of the variation of the volume, it's density will vary too. The density can be calculated by the expression:

ρ₁ = ρ₀/(1 + β*(t₁ - t₀))

Where ρ₁ is the final density, ρ₀ the initial density, β is the constant coefficient of volume expansion, t₁ the final temperature, and t₀ the initial temperature.

At t₀ = 4°C, the water desity is ρ₀ = 1,000 kg/m³. The value of the constant for water is β = 0.0002 m³/m³ °C, so, for t₁ = 93°C

ρ₁ = 1,000/(1 + 0.0002*(93 - 4))

ρ₁ = 1,000/(1+ 0.0178)

ρ₁ = 982.5 kg/m³

3 0
4 years ago
Review this balanced neutralization reaction: HBr + KOH KBr + H2O. Which substance is the base?
Olegator [25]
B KOH
I would say this is the base for the compound substance
8 0
3 years ago
An experiment to measure the enthalpy change for the reaction of aqueous
Komok [63]

Given that, an experiment to measure the enthalpy change for the reaction of aqueous copper(II) sulfate, CuSO4(aq) and zinc, Zn(s) was carried out in a coffee cup calorimeter; the heat of the reaction in the whole system is calculated to be 2218.34 kJ

Heat of reaction (i.e enthalpy of reaction) is the quantity of heat that is required to be added or removed when a chemical reaction is taken place in order to maintain all of the compounds present at the same temperature.

The formula used to calculate the heat of the reaction can be expressed as follows:

Q = mcΔT

where:

  • Q = quantity of heat transfer
  • m = mass
  • c = specific heat of water = 4.18 kJ/g °C (constant)
  • ΔT = change in temparature

From the information given:

  • The initial temperature (T₁) = 25° C
  • The final temperature (T₂) = 91.5° C

∴

The change in temperature i.e. ΔT = T₂ - T₁

ΔT = 91.5° C - 25° C

ΔT = 66.5° C

The number of moles of CuSO₄ = 1.00 mol/dm³ × 50.0 cm³

\mathbf{= (1 \times \dfrac{50}{1000})\ moles}

= 0.05 moles

  • Since the molar mass of CuSO₄ = 159.609 g/mol

Then;

Using the relation:

\mathbf{number \ of \ moles = \dfrac{mass}{molar \ mass}}}

By crossing multiplying;

mass of CuSO₄ = number of moles of CuSO₄ ×  molar mass of CuSO₄

mass of CuSO₄ = 0.05 moles  × 159.609 g/moles

mass of CuSO₄ = 7.9805 grams

∴

Using the formula from above:

Q = mcΔT

Q = 7.9805 g × 4.18 kJ/g °C × 66.5° C

Q = 2218.34 kJ

Therefore, we can conclude that the heat of the reaction is 2218.34 kJ

Learn more about the chemical reaction here:

brainly.com/question/20250226?referrer=searchResults

8 0
3 years ago
Titration of 0.824 g of potassium hydrogen phthalate required 38.314 g of naoh solution to reach the end point detected by pheno
melamori03 [73]

1.062 mol/kg.

<em>Step 1</em>. Write the balanced equation for the neutralization.

MM = 204.22 40.00

KHC8H4O4 + NaOH → KNaC8H4O4 + H2O

<em>Step 2</em>. Calculate the moles of potassium hydrogen phthalate (KHP)

Moles of KHP = 824 mg KHP × (1 mmol KHP/204.22 mg KHP)

= 4.035 mmol KHP

<em>Step 3</em>. Calculate the moles of NaOH

Moles of NaOH = 4.035 mmol KHP × (1 mmol NaOH/(1 mmol KHP)

= 4.035 mmol NaOH

<em>Step 4</em>. Calculate the mass of the NaOH

Mass of NaOH = 4.035 mmol NaOH × (40.00 mg NaOH/1 mmol NaOH)

= 161 mg NaOH

<em>Step 5</em>. Calculate the mass of the water

Mass of water = mass of solution – mass of NaOH = 38.134 g - 0.161 g

= 37.973 g

<em>Step 6</em>. Calculate the molal concentration of the NaOH

<em>b</em> = moles of NaOH/kg of water = 0.040 35 mol/0.037 973 kg = 1.062 mol/kg

3 0
4 years ago
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