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masya89 [10]
2 years ago
3

When looking at the percentage of patients whose symptoms were relieved after taking a placebo, a scientist sees a 20% success r

ate. The success rate of patients whose symptoms were relieved after taking a new composite drug was 30%. The scientist determines that the margin of error is 10%, which indicates that the new drug had no statistically significant positive effect. In which stage of the engineering process is this scientist? A. Looking for future improvements B. Identifying a need C. Evaluating test results D. Screening Chemistry
Chemistry
1 answer:
olga55 [171]2 years ago
4 0

the answer would be evaluating test results (apex)


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a metal worker uses a cutting torch that operates by reacting acetylene gas, C2H2(g), with oxygen gas, O2(g), as shown in the un
harkovskaia [24]

Answer:

650 grams

Explanation:

Given that acetylene gas reacts with oxygen to produce caobon dioxide, water and heat and the unbalnced equation is

C_2H_2(g)+O_2(g) \rightarrow CO_2(g) + H_2O(g)+ heat

Gram-formula mass of C_2H_2= 26 g/mol

So, mass of 1 mole of acelylene is 26 grams

Therefore, mass of 25 moles of acelylene=25x26=650 grams

Hence, the mass of 25 moles of acelylene is 650 grams

8 0
2 years ago
Read 2 more answers
How many grams of nano3 would you add to 500g of h2o in order to prepare a solution that is 0.500 molal in nano3?
VARVARA [1.3K]
When the concentration is expressed in molality, it is expressed in moles of solute per kilogram of solvent. Since we are given the mass of the solvent, which is water, we can compute for the moles of solute NaNO3.

0.5 m = x mol NaNO3/0.5 kg water
x = 0.25 mol NaNO3

Since the molar mass of NaNO3 is 85 g/mol, the mass is

0.25 mol * 85 g/mol = 21.25 grams NaNO3 needed
4 0
2 years ago
The dipole moment (μ) of HBr (a polar covalent molecule) is 0.838D (debye), and its percent ionic character is 12.4 % . Estimate
myrzilka [38]

<span>When two electrical charges, of opposite sign and equal magnitude, are separated by a distance, a dipole is established. The size of a dipole is measured by its dipole moment (</span>μμ). Dipole moment is measured in Debye units, which is equal to the distance between the charges multiplied by the charge (1 Debye equals 3.34×10−30Cm3.34×10−30Cm). The dipole moment of a molecule can be calculated by Equation 1.11.1:

μ = qr

where

<span> <span>μ⃗ μ→ is the dipole moment vector</span> <span>qiqi is the magnitude of the ithith charge, and</span> <span>r⃗ ir→i is the vector representing the position of ithith charge.</span> </span>

 

r = μ/q

<span>r = [0.838D(3.34×10−30 C⋅m/ 1D)]/ (1.6×10−19 C) *0.124
</span> r = 1.41 x10^-10 m

 

7 0
2 years ago
Read 2 more answers
Be sure to answer all parts. Consider the following reaction: Cd(s) + Fe2+(aq) → Cd2+(aq) + Fe(s) E o (Fe2+ / Fe) = −0.4400 V, E
Bezzdna [24]

Answer:

EMF = -0.17 V

No

Explanation:  

For the reaction :

Cd(s) + Fe2+(aq) → Cd2+(aq) + Fe(s)

we will be using the Nersnt equation to calculate Ecell:

Ecell =  Eº -0.0592 V/2 ln Q

where Q = ( Fe⁺² )/ (Cd²⁺)

and (Fe²⁺) and (Cd²) are the molar concentration of Fe²⁺ and Cd²⁺

Reduction

Fe²⁺ + 2e⁻  ⇒ Fe(s)      Eº red = -0.4400 V

Oxidation

Cd (s)   ⇒ Cd²⁺ + 2e⁻    Eº ox = +0.4000 V

Eºcell = Eox + Ered = 0.4000 V + (-0.4400 V) = -0. 0400 V

Ecell = Eº -0.0692 V/2 ln Q = -0.0400 V - 0.0592/2 ln ( 0.80/0.010 ) = -0.17V

No because Eºcell is negative and  ΔºG will be positive since

                               ΔºG  =  -nFEºcell

5 0
2 years ago
Which of these is a chemical property of a substance? texture ductility reactivity conductivity
beks73 [17]

Reactivity is a chemical property of a substance. According to EPA regulations, it is normally unstable and readily

undergoes violent change without detonating. it can explode or violently react when exposed to water, when heated, or under STP.

8 0
2 years ago
Read 2 more answers
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