Evaluation of Equilibrium Solubilities: statistics versus selected experiments 

Evaluation of Equilibrium Solubilities: statistics versus selected experiments | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluation of Equilibrium Solubilities: statistics versus selected experiments Wolfgang Voigt This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8501553/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Using the examples of the solubility of NaCl and NaNO 3 in water, the statistical treatment of all published data is compared with a selection of reports of 2–4 authors with particularly carefully performed and described solubility determinations. The uncertainties in the latter case are up to ten times smaller. For T < 100°C, such accurate work was published at the end of the 19th century. The temperature, when anhydrite, CaSO 4 , in contact with water starts to form gypsum, CaSO 4 ·2H 2 O, and vice versus can be predicted by the temperature of intersection of the solubility curves of both minerals. Exact knowledge of this temperature is of interest for the geoscience of evaporitic rocks and tunnel construction planning through sulfate-containing rocks. However, the uncertainty resulting from separate statistical treatment of the solubility data of gypsum and anhydrite results in too large an uncertainty. Experimental solubility determinations with focus on the intersection temperature are superior to statistical treatments and yield a temperature of (42.1 ± 1.5) °C. In the system MgSO 4 – H 2 O, a series of stable hydrates occurs along the solubility curve of magnesium sulfate in dependence on temperature. Above 68°C, the monohydrate represents the stable phase, known as mineral kieserite, which is found in evaporitic rocks and was formed at ambient temperatures in solutions rich in MgCl 2 . Large amounts of magnesium sulfate hydrate on the surface of the planet Mars raise the question of whether the monohydrate represents a primary factor for water distribution control. Due to kinetic difficulties in achieving solubility equilibrium in the laboratory at low temperatures, thermodynamic modelling is applied to predict the low temperature limit for kieserite formation. It is shown that experimental evidence is still missing to confirm the model’s predictions. Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 25 Feb, 2026 Reviews received at journal 25 Feb, 2026 Reviews received at journal 20 Feb, 2026 Reviews received at journal 07 Feb, 2026 Reviewers agreed at journal 28 Jan, 2026 Reviewers agreed at journal 28 Jan, 2026 Reviewers agreed at journal 28 Jan, 2026 Reviewers invited by journal 28 Jan, 2026 Editor assigned by journal 05 Jan, 2026 Submission checks completed at journal 05 Jan, 2026 First submitted to journal 02 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8501553","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":581811320,"identity":"ae7a48ab-99ed-464d-85b6-9e1628897a61","order_by":0,"name":"Wolfgang Voigt","email":"data:image/png;base64,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","orcid":"","institution":"TU Bergakademie Freiberg","correspondingAuthor":true,"prefix":"","firstName":"Wolfgang","middleName":"","lastName":"Voigt","suffix":""}],"badges":[],"createdAt":"2026-01-02 14:23:48","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8501553/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8501553/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101752706,"identity":"d47101d1-14fa-4443-9bd1-ccc8c0d7c95b","added_by":"auto","created_at":"2026-02-03 10:29:03","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1345177,"visible":true,"origin":"","legend":"","description":"","filename":"UncertaintySolubility20251230.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8501553/v1_covered_f0ca6ea1-772d-433a-a0fc-43bb9b10c038.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of Equilibrium Solubilities: statistics versus selected experiments ","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-solution-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josl","sideBox":"Learn more about [Journal of Solution Chemistry](http://link.springer.com/journal/10953)","snPcode":"10953","submissionUrl":"https://submission.nature.com/new-submission/10953/3","title":"Journal of Solution Chemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8501553/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8501553/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eUsing the examples of the solubility of NaCl and NaNO\u003csub\u003e3\u003c/sub\u003e in water, the statistical treatment of all published data is compared with a selection of reports of 2\u0026ndash;4 authors with particularly carefully performed and described solubility determinations. The uncertainties in the latter case are up to ten times smaller. For T\u0026thinsp;\u0026lt;\u0026thinsp;100\u0026deg;C, such accurate work was published at the end of the 19th century.\u003c/p\u003e \u003cp\u003eThe temperature, when anhydrite, CaSO\u003csub\u003e4\u003c/sub\u003e, in contact with water starts to form gypsum, CaSO\u003csub\u003e4\u003c/sub\u003e\u0026middot;2H\u003csub\u003e2\u003c/sub\u003eO, and vice versus can be predicted by the temperature of intersection of the solubility curves of both minerals. Exact knowledge of this temperature is of interest for the geoscience of evaporitic rocks and tunnel construction planning through sulfate-containing rocks. However, the uncertainty resulting from separate statistical treatment of the solubility data of gypsum and anhydrite results in too large an uncertainty. Experimental solubility determinations with focus on the intersection temperature are superior to statistical treatments and yield a temperature of (42.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5) \u0026deg;C.\u003c/p\u003e \u003cp\u003eIn the system MgSO\u003csub\u003e4\u003c/sub\u003e \u0026ndash; H\u003csub\u003e2\u003c/sub\u003eO, a series of stable hydrates occurs along the solubility curve of magnesium sulfate in dependence on temperature. Above 68\u0026deg;C, the monohydrate represents the stable phase, known as mineral kieserite, which is found in evaporitic rocks and was formed at ambient temperatures in solutions rich in MgCl\u003csub\u003e2\u003c/sub\u003e. Large amounts of magnesium sulfate hydrate on the surface of the planet Mars raise the question of whether the monohydrate represents a primary factor for water distribution control. Due to kinetic difficulties in achieving solubility equilibrium in the laboratory at low temperatures, thermodynamic modelling is applied to predict the low temperature limit for kieserite formation. It is shown that experimental evidence is still missing to confirm the model\u0026rsquo;s predictions.\u003c/p\u003e","manuscriptTitle":"Evaluation of Equilibrium Solubilities: statistics versus selected experiments ","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-30 16:21:51","doi":"10.21203/rs.3.rs-8501553/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-25T21:55:49+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-25T20:35:51+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-20T10:22:55+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-07T08:42:08+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"284513616794945720804367235314408839653","date":"2026-01-28T12:43:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"112240653821872215416238262483267015266","date":"2026-01-28T12:10:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"23375742350071588022766900575543384504","date":"2026-01-28T11:30:33+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-28T10:44:04+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-06T04:28:14+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-06T04:27:58+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Solution Chemistry","date":"2026-01-02T14:18:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-solution-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josl","sideBox":"Learn more about [Journal of Solution Chemistry](http://link.springer.com/journal/10953)","snPcode":"10953","submissionUrl":"https://submission.nature.com/new-submission/10953/3","title":"Journal of Solution Chemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"4855e739-4d8e-476f-8df3-0b4d8e3b38e8","owner":[],"postedDate":"January 30th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-14T12:39:22+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-30 16:21:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8501553","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8501553","identity":"rs-8501553","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}