Some metal chips with a total volume of 3.29 cm3 are placed on a piece of paper and weighed. The combined mass is found to be 18.43 g, and the paper itself weighs 1.2140 g. Calculate the density of the metal to the proper number of significant figures.
in which of the following substances there is a greater number of moles? Ca=40 Na=23 He=4 Mg=24 Li=7
A. 5g of Ca
B. 2g of Na
C. 10g of He
D. 25g of Mg
E. 15g of Li
Why does the size of a hydrode ion varies with the metal ion to which it is bound?
Ammonium sulfate reacts with aqueous sodium hydroxide as shown by the equation below.
(NH4)2SO4 + 2NaOH à 2NH3 + Na2SO4 + 2H2O
A sample of ammonium sulfate was heated with 100.0 cm3 of 0.500 mol dm‐3 aqueous sodium hydroxide. To ensure that all the ammonium sulfate reacted, an excess of sodium hydroxide was used. Heating was continued until all of the ammonia had been driven off as a gas. The unreacted sodium hydroxide remaining in the solution required 27.3cm3 of 0.600 moldm‐3 hydrochloric acid for neutralisation.
Calculate the mass of ammonium sulfate in the sample.
A Student was asked to determine the percentage of CaCO3 present in 0.125g of chalk.
In the first step, the student placed the chalk sample in a 250cm3 conical flask and added 50cm3 of the 0.200moldm-3.
In the second step, excess HCl was then titrated with NaOH (0.25moldm-3). The average titre being 32.12cm3.
1. An impure sample of 0.6275g of K2CO3 (Mr 138.2g/mol) was dissolved in water to make up a solution of 200cm3. 20cm3 was pipetted out into a conical flask. It was titrated against 20cm3 of 0.17moldm-3 of HCl.
The excess HCl was then titrated against NaOH (0.1048moldm-3 and average titre of 24.16cm3). Calculate the percentage by mass of the original sample of K2CO3
I take 5g of solid-liquid mixture sample,after acid digestion and make up to 50ml,from which I take 10 ml for chloride analysis,there 0.2ml AgNO3 consumed after back titration against 0.02N AgNO3 and NH4SCN.
how to calculate the chloride in the original sample? unit of result as mg/L or mg/kg?
if the molar mass of H2SO4 is 98.09 g/mol . how many grams of H2SO4 are in one mole of this substance?
when 2.76 g (0.02 mol) of kco was added to 30,0 cm3 of app 2 mol dm-3 HCl the temperature rose by 5.2 degrees celcius. write a balanced equation, calculate the enthalpy change of this reaction per mole of k2co3. the specific heat capacities of solution are 4.2Jg-1k-1 and all solutions have a density of 1.0 gcm-3